# Timeline of Montana history

This timeline is a chronology of significant events in the history of the U.S. State of Montana and the historical area now occupied by the state.

## 2020s

| Year | Date | Event |
| 2024 | November 5 | The 2024 General Election will be held on November 5, 2024. |
| 2022 | November 8 | In the 2022 general election, Montana voters elect Ryan Zinke as the U.S. representative for the new 1st congressional district and U.S. representative at-large Matt Rosendale for the new 2nd Congressional District. Republicans retain control of the Montana Legislature. |
| 2020 | November 3 | In the 2020 General Election, Montana voters elect three presidential electors for Donald Trump, re-elect Steve Daines as junior U.S. Senator, elect Matt Rosendale as U.S. representative at-large, and elect Greg Gianforte as Governor. Republicans retain control of the Montana Legislature. |
| 2020 | April 1 | The 2020 United States census enumerates the population of the State of Montana, later determined to be 1,084,225, an increase of 9.58% since the 2010 United States census. Montana remains the 44th most populous of the 50 U.S. states, but will gain a second Congressional seat. |

## 2010s

| Year | Date | Event |
| 2019 | December 2 | Governor Steve Bullock announces the end of his campaign for President of the United States. |
| 2019 | January 7 | Governor Steve Bullock announces his candidacy for President of the United States. |
| 2018 | December 15 | Ryan Zinke resigns as United States Secretary of the Interior following congressional investigations. |
| 2018 | November 6 | In the 2018 General Election, Montana voters re-elect Jon Tester as senior U.S. Senator and elect Greg Gianforte as U.S. representative at-large. Republicans retain control of the Montana Legislature. |
| 2018 | October 18 | At a political rally in Missoula, U.S. President Donald Trump congratulates Congressman Greg Gianforte for his assault of reporter Ben Jacobs. |
| 2017 | May 25 | In the special congressional replacement election, Montana voters elect Greg Gianforte U.S. representative at-large. |
| 2017 | May 24 | Congressional candidate Greg Gianforte assaults reporter Ben Jacobs. |
| 2017 | March 1 | U.S. representative at-large Ryan Zinke is confirmed and assumes office as United States Secretary of the Interior. |
| 2016 | November 8 | In the 2016 general election, Montana voters elect three presidential electors for Donald Trump, re-elect Ryan Zinke as U.S. representative at-large, and re-elect Steve Bullock as Governor. Republicans retain control of the Montana Legislature. |
| 2015 | January 3 | Steve Daines assumes office as the junior United States senator for the State of Montana. |
| 2014 | November 4 | In the 2014 General Election, Montana voters elect Steve Daines as junior U.S. Senator and elect Ryan Zinke as U.S. representative at-large. Republicans retain control of the Montana Legislature. |
| 2013 | January 7 | Steve Bullock assumes office as the 24th governor of the State of Montana. |
| 2012 | November 6 | In the 2012 general election, Montana voters elect three presidential electors for Mitt Romney, re-elect Jon Tester as senior U.S. Senator, elect Steve Daines as U.S. representative at-large, and elect Steve Bullock as governor. Republicans retain control of the Montana Legislature. |
| 2010 | November 2 | In the 2010 general election, Montana voters re-elect Denny Rehberg as U.S. representative at-large. Republicans retain control of the Montana Senate and regain control of the Montana House of Representatives. |
| 2010 | April 1 | The 2010 United States census enumerates the population of the State of Montana, later determined to be 989,415, an increase of 9.7% since the 2000 United States census. Montana remains the 44th most populous of the 50 U.S. states. |

## 2000s

| Year | Date | Event |
| 2009 | March 30 | U.S. President Barack Obama signs An Act to designate certain land as components of the National Wilderness Preservation System, to authorize certain programs and activities in the Department of the Interior and the Department of Agriculture, and for other purposes, creating the Pacific Northwest National Scenic Trail and the Ice Age Floods National Geologic Trail. |
| 2007 | January 3 | Jon Tester assumes office as the junior United States senator for the State of Montana. |
| 2005 | January 3 | Brian Schweitzer assumes office as the 23rd Governor of the State of Montana. |
| 2001 | January 17 | U.S. President Bill Clinton issues an executive orders creating Pompeys Pillar National Monument and Upper Missouri River Breaks National Monument. |
| 2001 | January 1 | Judy Martz assumes office as the 22nd Governor of the State of Montana. |
| 2000 | April 1 | The 2000 United States census enumerates the population of the State of Montana, later determined to be 902,195, an increase of 12.9% since the 1990 United States census. Montana remains the 44th most populous of the 50 U.S. states. |

## 1990s

| Year | Date | Event |
| 1995 | December 9 | The United Nations Educational, Scientific and Cultural Organization (UNESCO) designates Waterton-Glacier International Peace Park as a World Heritage Site. |
| 1993 | January 4 | Marc Racicot assumes office as the 21st Governor of the State of Montana. |
| 1992 | October 30 | U.S. President George H. W. Bush signs An Act to amend the Act of May 15, 1965, authorizing the Secretary of the Interior to designate the Nez Perce National Historical Park in the State of Idaho, and for other purposes. The Nez Perce National Historical Park now includes the Big Hole National Battlefield and the Bear Paw Battlefield in Montana. |
| 1991 | December 10 | U.S. President George H. W. Bush signs An Act of Congress changing the name of the Custer Battlefield National Monument to the Little Bighorn Battlefield National Monument. |
| 1990 | April 1 | The 1990 United States census enumerates the population of the State of Montana, later determined to be 786,690, an increase of 1.6% since the 1980 United States census. Montana remains the 44th most populous of the 50 U.S. states, but will lose its 2nd Congressional District. |

## 1980s

| Year | Date | Event |
| 1989 | January 2 | Stan Stephens assumes office as the 20th Governor of the State of Montana. |
| 1986 | October 6 | U.S. President Ronald Reagan signs An Act to amend the National Trails System Act by designating the Nez Perce (Nee-Me-Poo) Trail as a component of the National Trails System, creating the Nez Perce National Historic Trail. |
| 1981 | January 5 | Ted Schwinden assumes office as the 19th Governor of the State of Montana. |
| 1980 | April 1 | The 1980 United States census enumerates the population of the State of Montana, later determined to be 786,690, an increase of 13.3% since the 1970 United States census. Montana becomes the 44th most populous of the 50 U.S. states. |

## 1970s

| Year | Date | Event |
| 1978 | November 10 | U.S. President Jimmy Carter signs the National Parks and Recreation Act of 1978 authorizing the Lewis and Clark National Historic Trail and the Continental Divide National Scenic Trail. |
| 1978 | October 9 | The United Nations Educational, Scientific and Cultural Organization (UNESCO) designates Yellowstone National Park as one of the first 12 World Heritage Sites. |
| 1976 | July 4 | The State of Montana celebrates the Bicentennial of the United States of America. |
| 1973 | January 1 | Thomas Lee Judge assumes office as the 18th Governor of the State of Montana. |
| 1972 | August 25 | U.S. President Richard Nixon signs An Act to authorize the establishment of the Grant Kohrs Ranch National Historic Site in the State of Montana, and for other purposes. |
| 1970 | April 1 | The 1970 United States census enumerates the population of the State of Montana, later determined to be 694,409, an increase of 2.9% since the 1960 United States census. Montana becomes the 43rd most populous of the 50 U.S. states. |

## 1960s

| Year | Date | Event |
| 1969 | January 6 | Forrest H. Anderson assumes office as the 17th Governor of the State of Montana. |
| 1968 | December 2 | U.S. President Lyndon B. Johnson signs An Act to establish a national trails system, and for other purposes, creating the National Trails System. |
| 1966 | October 15 | U.S. President Lyndon B. Johnson signs An Act to provide for the establishment of the Bighorn Canyon National Recreation Area, and for other purposes. |
| 1966 | June 20 | The National Park Service establishes Fort Union Trading Post National Historic Site. |
| 1965 | July 1 | The State of Montana changes the name of the Agricultural College of the State of Montana to Montana State University. |
| 1963 | May 17 | U.S. President John F. Kennedy signs An Act to redesignate the Big Hole Battlefield National Monument, to revise the boundaries thereof, and for other purposes, changing the name of Big Hole Battlefield National Monument to Big Hole National Battlefield. |
| 1962 | January 25 | Lieutenant Governor Tim Babcock assumes office as the 16th Governor of the State of Montana |
| 1961 | January 2 | Donald Grant Nutter assumes office as the 15th Governor of the State of Montana. |
| 1960 | April 1 | The 1960 United States census enumerates the population of the State of Montana, later determined to be 674,767, an increase of 14.2% since the 1950 United States census. Montana becomes the 41st most populous of the 50 U.S. states. |

## 1950s

| Year | Date | Event |
| 1953 | January 5 | J. Hugo Aronson assumes office as the 14th Governor of the State of Montana. |
| 1950 | April 1 | The 1950 United States census enumerates the population of the State of Montana, later determined to be 591,024, an increase of 5.6% since the 1940 United States census. Montana becomes the 42nd most populous of the 48 U.S. states. |

## 1940s

| Year | Date | Event |
| 1949 | January 3 | John W. Bonner assumes office as the 13th Governor of the State of Montana. |
| 1946 | March 22 | Custer Battlefield National Monument. |
| 1945 | September 2 | World War II ends as the Empire of Japan formally surrenders. |
| 1945 | May 8 | The war in Europe ends as the Greater German Empire formally surrenders. |
| 1941 | December 11 | The United States declares war on the German Reich and the Italian Empire. |
| 1941 | December 8 | The United States declares war on the Empire of Japan and enters World War II. |
| 1941 | January 6 | Sam C. Ford assumes office as the 12th Governor of the State of Montana. |
| 1940 | April 1 | The 1940 United States census enumerates the population of the State of Montana, later determined to be 559,456, an increase of 4.1% since the 1930 United States census. Montana remains the 39th most populous of the 48 U.S. states. |

## 1930s

| Year | Date | Event |
| 1937 | August 24 | U.S. President Franklin D. Roosevelt signs An Act authorizing the Secretary of the Interior to convey certain land to the State of Montana to be used for the purposes of a public park and recreational site, transferring Lewis and Clark Cavern National Monument to the State of Montana to become Lewis and Clark Caverns State Park. |
| 1937 | July 22 | U.S. President Franklin D. Roosevelt signs An Act to create the Farmers' Home Corporation, to promote more secure occupancy of farms and farm homes, to correct the economic instability resulting from some present forms of farm tenancy, and for other purposes, also known as the Bankhead-Jones Farm Tenant Act. |
| 1937 | January 4 | Roy E. Ayers assumes office as the 11th Governor of the State of Montana. |
| 1935 | December 15 | President of the Montana Senate Elmer Holt assumes office as the tenth Governor of the State of Montana upon the death of Governor Frank Henry Cooney. |
| 1933 | March 13 | Lieutenant Governor Frank Henry Cooney assumes office as the ninth Governor of the State of Montana upon the resignation of Governor John E. Erickson. |
| 1932 | June 18 | The United States of America and Canada create the Waterton-Glacier International Peace Park. |
| 1930 | April 1 | The 1930 United States census enumerates the population of the State of Montana, later determined to be 537,606, a decrease of -2.1% since the 1920 United States census. Montana remains the 39th most populous of the 48 U.S. states. |

## 1920s

| Year | Date | Event |
| 1925 | January 4 | John E. Erickson assumes office as the eighth Governor of the State of Montana. |
| 1924 | November 24 | The State of Montana creates Petroleum County. |
| 1924 | June 2 | U.S. President Calvin Coolidge signs An Act To authorize the Secretary of the Interior to issue certificates of citizenship to Indians, also known as the Indian Citizenship Act of 1924, finally granting full United States Citizenship to all Native Americans born in the United States. |
| 1923 | May 11 | The State of Montana creates Lake County. |
| 1921 | January 3 | Joseph M. Dixon assumes office as the seventh Governor of the State of Montana. |
| 1920 | December 10 | The State of Montana creates Judith Basin County. |
| 1920 | October 4 | The State of Montana creates Golden Valley County. |
| 1920 | August 30 | The State of Montana creates Daniels County. |
| 1920 | April 1 | The 1920 United States census enumerates the population of the State of Montana, later determined to be 548,889, an increase of 46.0% since the 1910 United States census. Montana becomes the 39th most populous of the 48 U.S. states. |
| 1920 | February 11 | The State of Montana creates Liberty County. |

## 1910s

| Year | Date | Event |
| 1919 | March 7 | The State of Montana creates Powder River County. |
| 1919 | February 20 | The State of Montana creates McCone County. |
| 1919 | February 18 | The State of Montana creates Roosevelt County. |
| 1919 | February 17 | The State of Montana creates Glacier County and Pondera County. |
| 1919 | February 7 | The State of Montana creates Garfield County and Treasure County. |
| 1918 | November 11 | An armistice halts the Great War. |
| 1917 | April 6 | The United States declares war on the German Empire and enters the Great War. |
| 1917 | February 22 | The State of Montana creates Carter County and Wheatland County. |
| 1916 | August 25 | U.S. President Woodrow Wilson signs An Act To establish a National Park Service, and for other purposes. |
| 1915 | February 5 | The State of Montana creates Phillips County and Prairie County. |
| 1914 | August 17 | The State of Montana creates Wibaux County. |
| 1914 | August 7 | The State of Montana creates Mineral County. |
| 1914 | May 27 | The State of Montana creates Richland County. |
| 1914 | May 7 | The State of Montana creates Toole County. |
| 1913 | December 9 | The State of Montana creates Fallon County. |
| 1913 | March 24 | The State of Montana creates Sheridan County and Stillwater County. |
| 1913 | January 13 | The State of Montana creates Big Horn County. |
| 1913 | January 6 | Sam V. Stewart assumes office as the sixth Governor of the State of Montana. |
| 1912 | February 29 | The State of Montana creates Blaine County. |
| 1912 | February 28 | The State of Montana creates Hill County. |
| 1911 | February 11 | The State of Montana creates Musselshell County. |
| 1910 | June 23 | U.S. President William Howard Taft issues a proclamation creating Big Hole Battlefield National Monument. |
| 1910 | May 11 | U.S. President William Howard Taft signs An Act to establish "The Glacier National Park" in the Rocky Mountains south of the international boundary line, in the State of Montana, and for other purposes. |
| 1910 | April 1 | The 1910 United States census enumerates the population of the State of Montana, later determined to be 376,053, an increase of 54.5% since the 1900 United States census. Montana becomes the 40th most populous of the 46 U.S. states and gains a second Congressional seat. |

## 1900s

| Year | Date | Event |
| 1909 | March 9 | The State of Montana creates Lincoln County. |
| 1908 | July 2 | U.S. President Theodore Roosevelt issues executive orders creating Jefferson National Forest, Custer National Forest, and Sioux National Forest. |
| 1908 | July 1 | U.S. President Theodore Roosevelt issues an executive order re-establishing Absaroka National Forest. |
| 1908 | July 1 | U.S. President Theodore Roosevelt issues executive orders creating Beaverhead National Forest, Deerlodge National Forest, and Bitterroot National Forest. |
| 1908 | June 30 | U.S. President Theodore Roosevelt issues an executive order creating Beartooth National Forest. |
| 1908 | June 25 | U.S. President Theodore Roosevelt issues executive orders creating Blackfeet National Forest and Flathead National Forest. |
| 1908 | April 1 | Lieutenant Governor Edwin L. Norris assumes office as the fifth Governor of the State of Montana. |
| 1907 | March 2 | U.S. President Theodore Roosevelt issues a proclamation renaming the Lewis & Clarke Forest Reserve as the Lewis & Clark Forest Reserve. |
| 1907 | March 2 | U.S. President Theodore Roosevelt issues proclamations creating the Little Rockies Forest Reserve, the Cabinet Forest Reserve, and the Otter Forest Reserve. |
| 1906 | November 6 | U.S. President Theodore Roosevelt issues proclamations creating the Little Belt Forest Reserve, the Pryor Mountains Forest Reserve, and the Missoula Forest Reserve. |
| 1906 | November 5 | U.S. President Theodore Roosevelt issues proclamations creating the Ekalaka Forest Reserve, the Snowy Mountains Forest Reserve, and the Big Hole Forest Reserve. |
| 1906 | September 24 | U.S. President Theodore Roosevelt issues a proclamation creating the Long Pine Forest Reserve. |
| 1906 | September 20 | U.S. President Theodore Roosevelt issues a proclamation creating the Lolo Forest Reserve. |
| 1906 | August 13 | U.S. President Theodore Roosevelt issues a proclamation creating the Kootenai Forest Reserve. |
| 1906 | August 10 | U.S. President Theodore Roosevelt issues a proclamation creating the Crazy Mountains Forest Reserve. |
| 1906 | June 8 | U.S. President Theodore Roosevelt signs An Act For the preservation of American antiquities, also known as the Antiquities Act of 1906, giving the President of the United States the authority to create national monuments on federal lands to protect significant natural, cultural, or scientific features. |
| 1906 | April 12 | U.S. President Theodore Roosevelt issues a proclamation creating the Helena Forest Reserve. |
| 1905 | October 3 | U.S. President Theodore Roosevelt issues proclamations creating the Big Belt Forest Reserve, the Hell Gate Forest Reserve, and the Little Belt Forest Reserve. |
| 1905 | May 12 | U.S. President Theodore Roosevelt issues a proclamation creating the Elkhorn Forest Reserve. |
| 1905 | February 7 | The State of Montana creates Sanders County. |
| 1904 | June 14 | U.S. President Theodore Roosevelt issues a proclamation creating the Bitter Root Forest Reserve. |
| 1903 | January 29 | U.S. President Theodore Roosevelt issues a proclamation creating the Highwood Mountains Forest Reserve. |
| 1903 | January 29 | U.S. President Theodore Roosevelt issues a proclamation consolidating the Absaroka Forest Reserve into the Yellowstone Forest Reserve. |
| 1902 | September 4 | U.S. President Theodore Roosevelt issues a proclamation creating the Absaroka Forest Reserve. (Abolished January 29, 1903, but re-established July 1, 1908.) |
| 1902 | August 16 | U.S. President Theodore Roosevelt issues proclamations creating the Little Belt Mountains Forest Reserve and the Madison Forest Reserve. |
| 1901 | February 11 | The State of Montana creates Rosebud County. |
| 1901 | January 31 | The State of Montana creates Powell County. |
| 1901 | January 7 | Joseph Toole assumes office as the fourth Governor of the State of Montana. |
| 1900 | April 1 | The 1900 United States census enumerates the population of the State of Montana, later determined to be 243,329, an increase of 70.3% since the 1890 United States census. Montana becomes the 41st most populous of the 45 U.S. states. |

## 1890s

| Year | Date | Event |
| 1899 | February 10 | U.S. President Grover Cleveland issues a proclamation creating the Gallatin Forest Reserve. |
| 1898 | December 10 | The United States of America and the Kingdom of Spain sign the Treaty of Paris of 1898 to end the Spanish–American War. |
| 1898 | August 12 | The United States of America and the Kingdom of Spain sign a Protocol of Peace. |
| 1898 | April 23 | The Kingdom of Spain declares war on the United States of America. The United States declares war on Spain two days later. |
| 1897 | February 22 | U.S. President Grover Cleveland issues a proclamation creating the Bitter Root Forest Reserve, the Lewis & Clarke Forest Reserve, and the Flathead Forest Reserve. |
| 1897 | February 9 | The State of Montana creates Broadwater County. |
| 1897 | January 4 | Robert Burns Smith assumes office as the third Governor of the State of Montana. |
| 1895 | March 5 | The State of Montana creates Sweet Grass County. |
| 1895 | March 4 | The State of Montana creates Carbon County. |
| 1893 | March 2 | The State of Montana creates Granite County. |
| 1893 | February 16 | The State of Montana creates Ravalli County. |
| 1893 | February 16 | The State of Montana founds the Agricultural College of the State of Montana. |
| 1893 | February 13 | The State of Montana founds the University of Montana. |
| 1893 | February 7 | The State of Montana creates Teton County. |
| 1893 | February 6 | The State of Montana creates Flathead County and Valley County. |
| 1893 | January 2 | John E. Rickards assumes office as the second Governor of the State of Montana. |
| 1891 | March 3 | U.S. President Benjamin Harrison signs An act to repeal timber-culture laws, and for other purposes, also known as the Forest Reserve Act of 1891, giving the President of the United States the authority to create protected national forests on federal lands. |
| 1890 | April 1 | The 1890 United States census enumerates the population of the State of Montana, later determined to be 142,924, an increase of 265.0% since the 1880 United States census. Montana becomes the 41st most populous of the 43 U.S. states. |

## 1880s

| Year | Date | Event |
| 1889 | November 8 | Joseph Toole assumes office as the first Governor of the State of Montana. |
| 1889 | November 8 | U.S. President Benjamin Harrison issues Proclamation 293—Admission of Montana into the Union. The Territory of Montana becomes the State of Montana, the 41st U.S. state. |
| 1889 | April 9 | U.S. President Benjamin Harrison appoints Benjamin F. White the ninth (and last) Governor of the Territory of Montana. |
| 1889 | February 22 | U.S. President Grover Cleveland signs An Act to provide for the division of Dakota into two States and to enable the people of North Dakota, South Dakota, Montana, and Washington to form constitutions and State governments and to be admitted into the Union on an equal footing with the original States, and to make donations of public lands to such States. |
| 1887 | September 12 | The Territory of Montana creates Cascade County. |
| 1887 | February 23 | The Territory of Montana creates Park County. |
| 1887 | February 8 | U.S. President Grover Cleveland appoints Preston Leslie the eighth Governor of the Territory of Montana. |
| 1885 | July 14 | U.S. President Grover Cleveland appoints Samuel Thomas Hauser the seventh Governor of the Territory of Montana. |
| 1885 | March 12 | The Territory of Montana creates Fergus County. |
| 1884 | December 16 | U.S. President Chester A. Arthur appoints B. Platt Carpenter the sixth Governor of the Territory of Montana. |
| 1883 | July 13 | U.S. President Chester A. Arthur appoints John Schuyler Crosby the fifth Governor of the Territory of Montana. |
| 1883 | February 26 | The Territory of Montana creates Yellowstone County. |
| 1881 | February 16 | The Territory of Montana creates Silver Bow County. |
| 1880 | April 1 | The 1880 United States census enumerates the population of the Territory of Montana, later determined to be 39,159, an increase of 90.1% since the 1880 United States census. Montana becomes the sixth most populous of the eight U.S. territories. |

## 1870s

| Year | Date | Event |
| 1877 | September 30 | U.S. soldiers under the command of General Oliver Otis Howard attack Nez Perce people led by Chief Joseph attempting to flee to Canada in the Battle of Bear Paw. Chief Joseph and many Nez Perce are captured. |
| 1877 | September 13 | U.S. soldiers under the command of Colonel Samuel D. Sturgis attack Nez Perce people attempting to flee to Canada in the Battle of Canyon Creek. |
| 1877 | August 9 | U.S. soldiers under the command of Colonel John Gibbon attack Nez Perce people encamped in the Bitterroot Valley in the Battle of the Big Hole. |
| 1877 | February 16 | The Territory of Montana changes the name of Big Horn County to Custer County in honor of Lieutenant Colonel George Armstrong Custer. |
| 1876 | July 4 | The Territory of Montana celebrates the Centennial of the United States of America while still reeling from the Battle of the Little Bighorn. |
| 1876 | June 26 | The 7th Cavalry Regiment under the command of Lieutenant Colonel George Armstrong Custer are defeated at the Battle of the Little Bighorn by a force of Lakota, Northern Cheyenne, and Arapaho warriors. |
| 1875 | April 19 | The Territory of Montana selects Helena as the third Territorial Capital. Helena remains the capital of Montana. |
| 1872 | March 1 | U.S. President Ulysses S. Grant signs An Act to set apart a certain tract of land lying near the headwaters of the Yellowstone River as a public park, creating Yellowstone National Park, the world's first national park. |
| 1870 | July 13 | U.S. President Ulysses S. Grant appoints Benjamin F. Potts the fourth Governor of the Territory of Montana. |
| 1870 | April 1 | The 1870 United States census enumerates the population of the Territory of Montana, later determined to be 20,595. Montana is the sixth most populous of the nine U.S. territories. |

## 1860s

| Year | Date | Event |
| 1869 | April 9 | U.S. President Ulysses S. Grant appoints James Mitchell Ashley the third Governor of the Territory of Montana. |
| 1869 | January 15 | The Territory of Montana creates Dawson County. |
| 1868 | March 1 | The Territory of Montana changes the name of Edgerton County to Lewis and Clark County in honor of Meriwether Lewis and William Clark. |
| 1867 | November 16 | The Territory of Montana creates Meagher County. |
| 1866 | October 3 | U.S. President Andrew Johnson appoints Green Clay Smith the second Governor of the Territory of Montana. |
| 1865 | February 7 | The Territory of Montana selects Virginia City as the second Territorial Capital. |
| 1865 | February 2 | The Territory of Montana creates nine original counties: Beaverhead County, Big Horn County, Chouteau County, Deer Lodge County, Edgerton County, Gallatin County, Jefferson County, Madison County, and Missoula County. |
| 1864 | October 30 | The gold camp of Helena is established. |
| 1864 | September | Territorial Governor Sidney Edgerton arrives in Bannack, Montana Territory. |
| 1864 | July 14 | Four miners from the State of Georgia discover gold at Last Chance Gulch. |
| 1864 | June 22 | U.S. President Abraham Lincoln appoints Sidney Edgerton the first Governor of the Territory of Montana. |
| 1864 | May 28 | The provisional Montana Territorial Legislature selects Bannack as the first Territorial Capital. |
| 1864 | May 26 | U.S. President Abraham Lincoln signs An Act to provide a temporary Government for the Territory of Montana. |
| 1863 | June 16 | The Virginia City Mining District is established in the Territory of Idaho. |
| 1863 | May 26 | Bill Fairweather and Henry Edgar discover gold along Alder Creek in the Territory of Idaho. |
| 1863 | March 3 | U.S. President Abraham Lincoln signs An Act to provide a temporary Government for the Territory of Idaho. The Territory of Idaho includes all of the future State of Montana. |
| 1862 | July 28 | Gold is discovered along Grasshopper Creek in the Territory of Dakota. Bannack City is established nearby. |
| 1861 | April 12 | The American Civil War begins with the Battle of Fort Sumter. |
| 1861 | March 4 | Abraham Lincoln assumes office as the 16th President of the United States. |
| 1861 | March 2 | Outgoing U.S. President James Buchanan signs the An Act to provide a temporary government for the Territory of Dakota, and to create the office of surveyor general therein. The Territory of Dakota includes all of the future State of Montana east of the Continental Divide of the Americas. |
| 1861 | February 8 | The seven secessionist slave states create the Confederate States of America. |
| 1860 | November 6 | Abraham Lincoln is elected President of the United States. Seven slave states will secede from the United States of America before February 8, 1861. |
| 1860 | July 2 | The steamboats "Chippewa" and "Key West" arrive at the head of navigation of the Missouri River at Fort Benton, Montana. |
| 1860 | | The United States Government completes the Mullan Road between Fort Benton and Walla Walla, Washington. |
| 1860 | | Francis Lyman Worden and Captain Christopher P. Higgins found the settlement of Hell Gate near the future site of Missoula, Montana. |

## 1850s

| Year | Date | Event |
| 1858 | May 12 | Brothers James and Granville Stuart discover gold at Gold Creek near the future site of Drummond, Montana. |
| 1855 | July 16 | Isaac Stevens, the first Governor of the Territory of Washington, concludes the Hellgate treaty with Salish, Pend d'Oreille and Kootenai chiefs to establish the Jocko Reservation. |
| 1854 | May 30 | U.S. President Franklin Pierce signs An Act to Organize the Territories of Nebraska and Kansas. The Territory of Nebraska includes all of the future State of Montana east of the Continental Divide of the Americas. |
| 1853 | March 2 | U.S. President Millard Fillmore signs An Act to establish the Territorial Government of Washington. The Territory of Washington includes the portion of the future State of Montana lying west of the Continental Divide of the Americas. The rest of the future state remains unorganized United States territory. |
| 1852 | summer | Trapper Francois Finlay discovers flakes of gold in Benetsee Creek (later Gold Creek) in the Territory of Oregon. |

## 1840s

| Year | Date | Event |
| 1848 | August 14 | U.S. President James K. Polk signs An Act to Establish the Territorial Government of Oregon. The Territory of Oregon includes the portion of the future State of Montana lying west of the Continental Divide of the Americas. The rest of the future state remains unorganized United States territory. |
| 1848 | February 2 | The United States of America and United Mexican States sign the Treaty of Guadalupe Hidalgo to end the Mexican–American War. |
| 1846 | July 17 | The Oregon Treaty between the United States of America and the United Kingdom of Great Britain and Ireland takes effect. The 49th parallel north is set as the international border from the Strait of Georgia to the Lake of the Woods. All land in the future State of Montana becomes unorganized United States territory. |
| 1846 | May 13 | The United States declares war on the Mexican Republic. |
| 1846 | | Alexander Culbertson establishes Fort Benton, the last fur trading post on the Upper Missouri River. |
| 1841 | September 24 | French Jesuit priest Pierre Jean DeSmet arrives in the Bitterroot Valley and establishes St. Mary's Mission, the first Euro-American settlement in the future State of Montana |

## 1830s

| Year | Date | Event |
| 1832 | spring | The steamship Yellowstone makes its inaugural voyage from St. Louis to Fort Union and back. |

## 1820s

| Year | Date | Event |
| 1828 | spring | The American Fur Company establishes Fort Union on the Missouri River near its confluence with the Yellowstone River. |
| 1822 | March 10 | William Henry Ashley forms the Rocky Mountain Fur Company in St. Louis. The company operates it in Wyoming and Montana for twelve years. Jim Bridger, William Sublette and Jedediah Smith are among its corps of trappers. |
| 1821 | August 10 | The State of Missouri is admitted to the Union. The rest of the Territory of Missouri becomes unorganized United States territory. |
| 1821 | March 2 | U.S. President James Monroe signs An Act to authorize the people of the Missouri territory to form a constitution and state government, and for the admission of such state into the Union on an equal footing with the original states, and to prohibit slavery in certain territories. |

## 1810s

| Year | Date | Event |
| 1819 | January 30 | The Treaty of 1818 between the United States of America and the United Kingdom of Great Britain and Ireland takes effect. The treaty calls for the joint occupation of the Oregon Country west of the Continental Divide of the Americas, and the 49th parallel north as the international border east of the Continental Divide to the Lake of the Woods. The Continental Divide separates the future State of Montana between the Oregon Country and the Territory of Missouri. |
| 1814 | | William Clark publishes A Map of Lewis and Clark's Track Across the Western Portion of North America. |
| 1812 | October 1 | The Territory of Missouri creates St. Charles County which includes all land in the future State of Montana in the Missouri River watershed. |
| 1812 | June 4 | U.S. President James Madison signs An Act providing for the government of the territory of Missouri. The Territory of Louisiana is renamed the Territory of Missouri. The Territory of Missouri includes all land in the future State of Montana in the Missouri River watershed. |
| 1810 | February 26 | Canadian fur trader and explorer David Thompson encounters Salish Indians wintering on the Flathead River below Flathead Lake. |

## 1800s

| Year | Date | Event |
| 1809 | November 9 | Canadian fur trader and explorer David Thompson establishes Saleesh House at Thompson Falls on the Columbia River. |
| 1807 | November 21 | Fur trader Manuel Lisa establishes Fort Raymond at the confluence of the Big Horn River with the Yellowstone River. |
| 1806 | September 23 | The Lewis and Clark Expedition arrives in St. Louis in the Territory of Louisiana (the future State of Missouri). |
| 1806 | August 11 | The Lewis and Clark Expedition reunites at the confluence of the Yellowstone River with the Missouri River. |
| 1806 | July 7 | William Clark and the other members of the Lewis and Clark Expedition cross the Continental Divide of the Americas at the saddle now known as Big Hole Pass. |
| 1806 | July 7 | Meriwether Lewis and nine other members of the Lewis and Clark Expedition cross the Continental Divide of the Americas at the saddle now known as Lewis and Clark Pass. |
| 1806 | July 3 | On their return east, Meriwether Lewis and William Clark decide to split their expedition to search for a shorter route to the Missouri River. |
| 1806 | March 22 | The Lewis and Clark Expedition depart Fort Clatsop and begin their voyage back to the United States. |
| 1805 | December 7 | The Lewis and Clark Expedition arrive at the site of their winter encampment on the south side of the Columbia River and begin the construction of Fort Clatsop. |
| 1805 | August 12 | Meriwether Lewis and three other members of the Lewis and Clark Expedition cross the Continental Divide of the Americas at the saddle now known as Lemhi Pass and enter territory claimed by Native Americans, the Kingdom of Spain, the United Kingdom of Great Britain and Ireland, and the Russian Empire. The rest of the expedition will follow. |
| 1805 | June 13 | The Lewis and Clark Expedition reaches the Great Falls of the Missouri River. It will take four weeks to portage the falls. |
| 1805 | April | The Lewis and Clark Expedition travels up the Missouri River and enters the future State of Montana. |
| 1805 | March 3 | U.S. President Thomas Jefferson signs An Act further providing for the government of the district of Louisiana. The District of Louisiana is reorganized as the self-governing Territory of Louisiana. The Territory of Louisiana includes all land in the future State of Montana in the Missouri River watershed. |
| 1804 | October 1 | The District of Louisiana is organized under the jurisdiction of the Territory of Indiana. |
| 1804 | May 21 | The Lewis and Clark Expedition departs St. Charles in the District of Louisiana (the future State of Missouri) and begins its voyage up the Missouri River. |
| 1804 | March 26 | U.S. President Thomas Jefferson signs An Act erecting Louisiana into two territories, and providing for the temporary government thereof. The portion of the Louisiana Purchase north of the 33rd parallel north is designated the military District of Louisiana. |
| 1803 | December 20 | The French Republic turns its colony of La Louisiane over to the United States. All land in the future State of Montana in the Missouri River watershed becomes unorganized United States territory. |
| 1803 | April 30 | The United States and the French Republic sign the Louisiana Purchase Treaty. |
| 1800 | October 1 | Under pressure from Napoléon Bonaparte, the Kingdom of Spain transfers the colony of la Luisiana back to the French Republic with the secret Third Treaty of San Ildefonso. |

## 1780s

| Year | Date | Event |
| 1783 | September 3 | The Treaty of Paris is signed in Paris by representatives of King George III of Great Britain and representatives of the United States of America. The treaty affirms the independence of the United States and sets the Mississippi River as its western boundary. |

## 1770s

| Year | Date | Event |
| 1776 | July 4 | Representatives of the thirteen United States of America sign the Declaration of Independence from the Kingdom of Great Britain. |

## 1760s

| Year | Date | Event |
| 1762 | November 13 | Fearing the loss of its American territories in the Seven Years' War, the Kingdom of France transfers its colony of La Louisiane to the Kingdom of Spain with the secret Treaty of Fontainebleau. |

## 1680s

| Year | Date | Event |
| 1682 | April 9 | René-Robert Cavelier, Sieur de La Salle, claims the Mississippi River and its watershed for the Kingdom of France and names the region La Louisiane in honor of King Louis XIV. The Mississippi Basin is later determined to be the fourth most extensive on Earth and includes lands inhabited by hundreds of thousands of native peoples and lands previously claimed by Spain, France, and England. The Louisiane claim includes all land in the future State of Montana east of the Continental Divide of the Americas. This will set up a rivalry among native peoples, France, Spain, and eventually the United States in the area. |

## 1540s

| Year | Date | Event |
| 1541 | June 28 | A Spanish military expedition led by Hernando de Soto, Governor of Cuba, become the first Europeans to cross the Mississippi River. |

## 1510s

| Year | Date | Event |
| 1513 | September 29 | Spanish conquistador Vasco Núñez de Balboa crosses the Isthmus of Panama and arrives on the shore of a sea that he names Mar del Sur (the South Sea, later named the Pacific Ocean). He claims the sea and all adjacent lands for the Queen of Castile. This includes the portion of the future State of Montana west of the Continental Divide of the Americas. |

## 1490s

| Year | Date | Event |
| 1493 | May 5 | Pope Alexander VI (born Roderic de Borja in Valencia) issues the papal bull Inter caetera which splits the non-Christian world into two halves. The eastern half goes to the King of Portugal for his exploration, conquest, conversion, and exploitation. The western half (including all of North America) goes to the Queen of Castile and the King of Aragon for their exploration, conquest, conversion, and exploitation. The indigenous peoples of the Americas have no idea that any of these people exist. |
| 1492 | October 12 | Genoese seaman Cristòffa Cómbo (Christopher Columbus) leading an expedition for Queen Isabella I of Castile lands on the Lucayan island of Guanahani that he renames San Salvador. This begins the Spanish conquest of the Americas. |

## Before 1492

| Era | Event |
| c. 12,000 BCE | During a centuries long period of warming, ice-age Paleoamericans from Beringia begin using the ice-free corridor east of the Rocky Mountains to migrate throughout the Americas. |