# Timeline of Arizona history

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

## 2020s

| Year | Date | Event |
| 2020 | November 3 | In the 2020 General Election, Arizona voters elect 11 U.S. Presidential Electors for Joe Biden, elect Mark Kelly as new U.S. Senator, and re-elect all nine incumbent U.S. Representatives. Republicans retain control of the Arizona State Legislature. |
| 2020 | April 1 | The 2020 United States Census enumerates the population of the State of Arizona, estimated to be about 7,388,000. Arizona may gain a 10th Congressional seat. |

## 2010s

| Year | Date | Event |
| 2019 | January 3 | Kyrsten Sinema and Martha McSally assume office as the U.S. Senators representing the State of Arizona. |
| 2015 | January 5 | Doug Ducey assumes office as the Governor of the State of Arizona. |
| 2013 | June 30 | 19 members of the Prescott Fire Department were killed fighting the Yarnell Hill Fire. |
| 2010 | April 1 | The 2010 United States Census enumerates the population of the State of Arizona, later determined to be 6,392,017, an increase of 24.6% since the 2000 United States Census. Arizona becomes the 16th most populous of the 50 U.S. states and gains a 9th Congressional District. |

## 2000s

| Year | Date | Event |
| 2009 | January 21 | Arizona Secretary of State Jan Brewer assumes office as the Governor of the State of Arizona upon the resignation of Governor Napolitano. |
| 2008 | November 4 | Arizona U.S. Senator John McCain losses the 2008 United States presidential election to Illinois U.S. Senator Barack Obama. |
| 2003 | March 6 | Janet Napolitano assumes office as the Governor of the State of Arizona. |
| 2001 | January 17 | U.S. President Bill Clinton issues an executive order creating Sonoran Desert National Monument. |
| 2000 | November 9 | U.S. President Bill Clinton issues an executive order creating Vermilion Cliffs National Monument. |
| 2000 | June 9 | U.S. President Bill Clinton issues an executive order creating Ironwood Forest National Monument. |
| 2000 | January 11 | U.S. President Bill Clinton issues an executive order creating Agua Fria National Monument and Grand Canyon–Parashant National Monument. |
| 2000 | April 1 | The 2000 United States Census enumerates the population of the State of Arizona, later determined to be 6,392,017, an increase of 40.0% since the 1990 United States Census. Arizona becomes the 20th most populous of the 50 U.S. states and gains a 7th Congressional District and an 8th Congressional District. |

## 1990s

| Year | Date | Event |
| 1997 | September 5 | Arizona Secretary of State Jane Dee Hull assumes office as the Governor of the State of Arizona upon the resignation of Governor Symington. |
| 1994 | August 6 | U.S. President Bill Clinton signs An Act to establish the Saguaro National Park in the State of Arizona, and for other purposes, creating Saguaro National Park from Saguaro National Monument. |
| 1991 | March 6 | Fife Symington assumes office as the Governor of the State of Arizona. |
| 1990 | August 6 | U.S. President George H. W. Bush signs An Act to establish the Tumacacori National Historical Park in the State of Arizona, creating Tumacacori National Historical Park from Tumacacori National Monument. |
| 1990 | April 1 | The 1990 United States Census enumerates the population of the State of Arizona, later determined to be 3,665,228, an increase of 34.8% since the 1980 United States Census. Arizona becomes the 24th most populous of the 50 U.S. states and gains a 6th Congressional District. |

## 1980s

| Year | Date | Event |
| 1988 | April 4 | Arizona Secretary of State Rose Mofford assumes office as the Governor of the State of Arizona upon the impeachment and removal from office of Governor Mecham. |
| 1987 | January 5 | Evan Mecham assumes office as the Governor of the State of Arizona. |
| 1987 | January 3 | John McCain assumes office as the junior U.S. senator representing the State of Arizona. |
| 1983 | January 1 | The State of Arizona creates La Paz County from a portion of Yuma County. |
| 1980 | April 1 | The 1980 United States Census enumerates the population of the State of Arizona, later determined to be 2,718,215, an increase of 55.7% since the 1970 United States Census. Arizona becomes the 29th most populous of the 50 U.S. states and gains a 5th Congressional District. |

## 1970s

| Year | Date | Event |
| 1978 | March 4 | Arizona Attorney General Bruce Babbitt assumes office as the Governor of the State of Arizona upon the death of Governor Bolin. |
| 1977 | October 20 | Arizona Secretary of State Wesley Bolin assumes office as the Governor of the State of Arizona upon the resignation of Governor Castro. |
| 1975 | January 6 | Raúl Héctor Castro assumes office as the Governor of the State of Arizona. |
| 1975 | January 3 | U.S. President Gerald Ford signs An Act to further protect the outstanding scenic, natural, and scientific values of the Grand Canyon by enlarging the Grand Canyon National Park in the State of Arizona, and for other purposes, annexing Grand Canyon National Monument and Marble Canyon National Monument to Grand Canyon National Park. |
| 1972 | October 21 | U.S. President Richard Nixon signs An Act to provide for the establishment of the Hohokam Pima National Monument in the vicinity of the Snaketown archeological site, Arizona, and for other purposes. |
| 1970 | April 1 | The 1970 United States Census enumerates the population of the State of Arizona, later determined to be 1,745,944, an increase of 34.1% since the 1960 United States Census. Arizona becomes the 33rd most populous of the 50 U.S. states and gains a 4th Congressional District. |

## 1960s

| Year | Date | Event |
| 1969 | July 25 | U.S. President Lyndon B. Johnson issues an executive order creating Marble Canyon National Monument. |
| 1967 | January 2 | Jack Williams assumes office as the Governor of the State of Arizona. |
| 1965 | August 28 | U.S. President Lyndon B. Johnson signs An Act to authorize the establishment of the Hubbell Trading Post National Historic Site, in the State of Arizona, and for other purposes. |
| 1965 | January 4 | Samuel Pearson Goddard Jr. assumes office as the Governor of the State of Arizona. |
| 1964 | November 3 | Senior Arizona U.S. Senator Barry Goldwater losses the 1964 United States presidential election to U.S. President Lyndon B. Johnson. |
| 1964 | July 25 | U.S. President Lyndon B. Johnson signs An Act to authorize the establishment of the Fort Bowie National Historic Site in the State of Arizona, and for other purposes. |
| 1960 | April 1 | The 1960 United States Census enumerates the population of the State of Arizona, later determined to be 1,302,161, an increase of 73.7% since the 1950 United States Census. Arizona becomes the 35th most populous of the 50 U.S. states and gains another Congressional seat to form the 1st, 2nd, 3rd Congressional Districts. |

## 1950s

| Year | Date | Event |
| 1959 | January 5 | Paul Fannin assumes office as the Governor of the State of Arizona. |
| 1958 | October 23 | U.S. President Dwight D. Eisenhower signs An Act to authorize the establishment of the Petrified Forest National Park in the State of Arizona, and for other purposes, creating Petrified Forest National Park from Petrified Forest National Monument. |
| 1955 | January 3 | Ernest McFarland assumes office as the Governor of the State of Arizona. |
| 1953 | October 23 | U.S. President Dwight D. Eisenhower signs Public Land Order 924 abolishing Crook National Forest and transferring its land to Coronado National Forest, Gila National Forest, and Tonto National Forest. |
| 1953 | January 3 | Barry Goldwater assumes office as the junior U.S. senator representing the State of Arizona. |
| 1952 | October 23 | U.S. President Harry S. Truman signs An Act To amend the Act entitled "An Act to provide for the establishment of the Coronado International Memorial, in the State of Arizona", approved August 18, 1941, creating Coronado National Memorial. |
| 1951 | January 1 | John Howard Pyle assumes office as the Governor of the State of Arizona. |
| 1950 | April 1 | The 1950 United States Census enumerates the population of the State of Arizona, later determined to be 749,587, an increase of 50.1% since the 1940 United States Census. Arizona becomes the 37th most populous of the 48 U.S. states. |

## 1940s

| Year | Date | Event |
| 1948 | May 25 | Arizona Secretary of State Dan Edward Garvey assumes office as the Governor of the State of Arizona upon the death of Governor Osborn. |
| 1941 | January 2 | Sidney Preston Osborn assumes office as the Governor of the State of Arizona. |
| 1940 | April 1 | The 1940 United States Census enumerates the population of the State of Arizona, later determined to be 499,261, an increase of 14.6% since the 1930 United States Census. Arizona remains the 43rd most populous of the 48 U.S. states but gains a 2nd Congressional seat. |

## 1930s

| Year | Date | Event |
| 1939 | July 25 | U.S. President Franklin D. Roosevelt issues an executive order creating Tuzigoot National Monument. |
| 1939 | January 2 | Robert Taylor Jones assumes office as the Governor of the State of Arizona. |
| 1937 | April 13 | U.S. President Franklin D. Roosevelt issues an executive order creating Organ Pipe Cactus National Monument. |
| 1937 | January 4 | Rawghlie Clement Stanford assumes office as the Governor of the State of Arizona. |
| 1934 | October 22 | U.S. President Franklin D. Roosevelt issues Executive Order 6882 merging Tusayan National Forest into Prescott National Forest. |
| 1933 | March 1 | U.S. President Herbert Hoover issues an executive order creating Saguaro National Monument. |
| 1933 | January 2 | Benjamin Baker Moeur assumes office as the Governor of the State of Arizona. |
| 1932 | December 22 | U.S. President Herbert Hoover issues an executive order creating a new Grand Canyon National Monument. |
| 1931 | December 22 | U.S. President Herbert Hoover issues an executive order creating Canyon de Chelly National Monument. |
| 1931 | January 5 | George W. P. Hunt assumes office as the Governor of the State of Arizona. |
| 1930 | May 26 | U.S. President Herbert Hoover issues an executive order creating Sunset Crater National Monument. |
| 1930 | April 7 | U.S. President Herbert Hoover signs An Act to abolish the Papago Saguaro National Monument, Arizona, to provide for the disposition of certain lands therein for park and recreational uses, and for other purposes, transferring Papago Saguaro National Monument to the State of Arizona. |
| 1930 | April 1 | The 1930 United States Census enumerates the population of the State of Arizona, later determined to be 435,573, an increase of 30.3% since the 1920 United States Census. Arizona becomes the 43rd most populous of the 48 U.S. states. |

## 1920s

| Year | Date | Event |
| 1929 | January 7 | John Calhoun Phillips assumes office as the Governor of the State of Arizona. |
| 1924 | December 9 | U.S. President Calvin Coolidge issues an executive order creating Wupatki National Monument. |
| 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. |
| 1924 | April 18 | U.S. President Calvin Coolidge issues an executive order creating Chiricahua National Monument. |
| 1923 | May 31 | U.S. President Warren G. Harding issues an executive order creating Pipe Spring National Monument. |
| 1923 | January 1 | George W. P. Hunt assumes office as the Governor of the State of Arizona. |
| 1920 | April 1 | The 1920 United States Census enumerates the population of the State of Arizona, later determined to be 334,162, an increase of 63.5% since the 1910 United States Census. Arizona becomes the 45th most populous of the 48 U.S. states |

## 1910s

| Year | Date | Event |
| 1919 | February 26 | U.S. President Woodrow Wilson signs An Act to establish the Grand Canyon National Park in the State of Arizona, creating Grand Canyon National Park from Grand Canyon National Monument. |
| 1919 | January 6 | Thomas Edward Campbell assumes office as the Governor of the State of Arizona. |
| 1918 | August 3 | U.S. President Woodrow Wilson issues an executive order creating Casa Grande National Monument from the Casa Grande Ruin Reservation. |
| 1917 | December 25 | George W. P. Hunt resumes office as the Governor of the State of Arizona following a court decision. |
| 1917 | June 6 | U.S. President Woodrow Wilson issues Executive Order 2630 merging Chiricahua National Forest into Coronado National Forest. |
| 1917 | January 1 | Thomas Edward Campbell assumes office as the Governor of the State of Arizona. |
| 1916 | August 25 | U.S. President Woodrow Wilson signs An Act To establish a National Park Service, and for other purposes. |
| 1915 | January 31 | U.S. President Woodrow Wilson issues an executive order creating Walnut Canyon National Monument. |
| 1914 | September 10 | U.S. President Woodrow Wilson issues Executive Order 2045 merging Zuni National Forest into Manzano National Forest. |
| 1914 | January 10 | U.S. President Woodrow Wilson issues an executive order creating Papago Saguaro National Monument. |
| 1912 | February 14 | George W. P. Hunt assumes office as the first Governor of the State of Arizona. |
| 1912 | February 14 | U.S. President William Howard Taft issues Proclamation 1180: Admitting Arizona to the Union. The Territory of Arizona becomes the State of Arizona, the 48th U.S. state. |
| 1911 | June 28 | U.S. President William Howard Taft issues Proclamation 1121 merging Garces National Forest into Coronado National Forest. |
| 1910 | June 28 | U.S. President William Howard Taft issues Proclamation 1049 creating Tusayan National Forest. |
| 1910 | June 20 | U.S. President William Howard Taft signs An Act to enable the people of New Mexico to form a constitution and state government and be admitted into the Union on an equal footing with the original States; and to enable the people of Arizona to form a constitution and state government and be admitted into the Union on an equal footing with the original States. |
| 1910 | April 1 | The 1910 United States Census enumerates the population of the Territory of Arizona, later determined to be 204,354, an increase of 66.2% since the 1900 United States Census. Arizona becomes the second most populous of the four U.S. territories. |

## 1900s

| Year | Date | Event |
| 1909 | September 15 | U.S. President William Howard Taft issues a proclamation creating Navajo National Monument. |
| 1909 | May 1 | U.S. President William Howard Taft appoints Richard Elihu Sloan as the 17th (and last) Governor of the Territory of Arizona. |
| 1909 | March 10 | The Territory of Arizona creates Greenlee County from a portion of Graham County. |
| 1909 | March 2 | U.S. President Theodore Roosevelt issues Proclamation 864 creating Zuni National Forest. |
| 1908 | September 15 | U.S. President Theodore Roosevelt issues a proclamation creating Tumacacori National Monument. |
| 1908 | July 2 | U.S. President Theodore Roosevelt issues Proclamation 909 creating Kaibab National Forest subsuming Grand Canyon National Forest. |
| 1908 | July 2 | U.S. President Theodore Roosevelt issues Proclamation 908 (1) creating Coronado National Forest subsuming Dragoon National Forest, Santa Catalina National Forest, and Santa Rita National Forest; and (2) creating Garces National Forest subsuming Baboquivari National Forest, Huachuca National Forest, and Tumacacori National Forest; and (3) merging Verde National Forest into Prescott National Forest. |
| 1908 | July 2 | U.S. President Theodore Roosevelt issues Proclamation 818 creating Coconino National Forest subsuming San Francisco Mountains National Forest. |
| 1908 | July 1 | U.S. President Theodore Roosevelt issues Proclamation 816 creating Crook National Forest subsuming Mount Graham National Forest. |
| 1908 | July 1 | U.S. President Theodore Roosevelt issues Proclamation 876 creating Apache National Forest. |
| 1908 | July 1 | U.S. President Theodore Roosevelt issues Proclamation 868 creating Sitgreaves National Forest. |
| 1908 | January 13 | U.S. President Theodore Roosevelt issues Procamation 795 merging Pinal Mountains National Forest into Tonto National Forest. |
| 1908 | January 11 | U.S. President Theodore Roosevelt issues a proclamation creating Grand Canyon National Monument. |
| 1907 | December 30 | U.S. President Theodore Roosevelt issues Proclamation 789 creating Verde National Forest. |
| 1907 | December 19 | U.S. President Theodore Roosevelt issues a proclamation creating Tonto National Monument. |
| 1907 | May 25 | U.S. President Theodore Roosevelt issues a proclamation creating Dragoon National Forest. |
| 1906 | December 8 | U.S. President Theodore Roosevelt issues proclamations creating Montezuma Castle National Monument and Petrified Forest National Monument, the first National Monuments in Arizona. |
| 1906 | November 7 | U.S. President Theodore Roosevelt issues a proclamation creating the Tumacacori Forest Reserve. |
| 1906 | November 6 | U.S. President Theodore Roosevelt issues a proclamation creating the Huachuca Forest Reserve. |
| 1906 | November 5 | U.S. President Theodore Roosevelt issues a proclamation creating the Baboquivari Forest Reserve. |
| 1906 | August 8 | U.S. President Theodore Roosevelt issues a proclamation changing the name of the Grand Cañon Forest Reserve to the Grand Canyon 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. |
| 1905 | October 3 | U.S. President Theodore Roosevelt issues a proclamation order creating the Tonto Forest Reserve. |
| 1905 | March 20 | U.S. President Theodore Roosevelt issues a proclamation creating the Pinal Mountains Forest Reserve. |
| 1905 | March 7 | U.S. President Theodore Roosevelt appoints Joseph Henry Kibbey as the 16th Governor of the Territory of Arizona. |
| 1902 | July 30 | U.S. President Theodore Roosevelt issues Proclamation 33 creating the Chiricahua Forest Reserve. |
| 1902 | July 22 | U.S. President Theodore Roosevelt issues Proclamation 31 creating the Mount Graham Forest Reserve. |
| 1902 | July 2 | U.S. President Theodore Roosevelt issues Proclamation 27 creating the Santa Catalina Forest Reserve. |
| 1902 | July 1 | U.S. President Theodore Roosevelt appoints Alexander Oswald Brodie as the 15th Governor of the Territory of Arizona. |
| 1902 | April 11 | U.S. President Theodore Roosevelt issues Proclamation 14 creating the Santa Rita Forest Reserve. |
| 1900 | April 1 | The 1900 United States Census enumerates the population of the Territory of Arizona, later determined to be 122,931, an increase of 39.3% since the 1890 United States Census. Arizona becomes the fourth most populous of the five U.S. territories. |

## 1890s

| Year | Date | Event |
| 1899 | March 15 | The Territory of Arizona creates Santa Cruz County from portions of Cochise County and Pima County. |
| 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 17 | U.S. President William McKinley issues Proclamation 19 creating the Black Mesa Forest Reserve. |
| 1898 | August 17 | U.S. President William McKinley issues Proclamation 18 creating the San Francisco Mountains Forest Reserve and the Black Mesa Forest Reserve. |
| 1898 | August 12 | The United States of America and the Kingdom of Spain sign a Protocol of Peace. |
| 1898 | August 1 | U.S. President William McKinley appoints Oakes Murphy as the 14th Governor of the Territory of Arizona. |
| 1898 | May 10 | U.S. President William McKinley issues Proclamation 9 creating the Prescott Forest Reserve. |
| 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 | July 29 | U.S. President William McKinley appoints Myron H. McCord as the 13th Governor of the Territory of Arizona. |
| 1896 | April 18 | U.S. President Grover Cleveland appoints Benjamin Joseph Franklin as the 12th Governor of the Territory of Arizona. |
| 1895 | March 21 | The Territory of Arizona creates Navajo County from a portion of Apache County. |
| 1893 | April 12 | U.S. President Grover Cleveland appoints L.C. Hughes as the 11th Governor of the Territory of Arizona. |
| 1893 | February 20 | U.S. President Benjamin Harrison issues Proclamation 45 creating the Grand Cañon Forest Reserve, the first National Forest in Arizona. |
| 1892 | May 11 | U.S. President Benjamin Harrison appoints Oakes Murphy as the tenth Governor of the Territory of Arizona. |
| 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. |
| 1891 | February 18 | The Territory of Arizona creates Coconino County from a portion of Yavapai County. |
| 1891 | January 21 | U.S. President Benjamin Harrison appoints John N. Irwin as the ninth Governor of the Territory of Arizona. |
| 1890 | April 1 | The 1890 United States Census enumerates the population of the Territory of Arizona, later determined to be 88,243, an increase of 218.2% since the 1880 United States Census. Arizona becomes the fifth most populous of the six U.S. territories. |

## 1880s

| Year | Date | Event |
| 1889 | April 8 | U.S. President Benjamin Harrison appoints Lewis Wolfley as the eighth Governor of the Territory of Arizona. |
| 1889 | March 2 | U.S. President Grover Cleveland issues an executive order creating the Casa Grande Ruin Reservation. |
| 1885 | November 2 | U.S. President Grover Cleveland appoints C. Meyer Zulick as the seventh Governor of the Territory of Arizona. |
| 1882 | March 8 | U.S. President Chester A. Arthur appoints Frederick Augustus Tritle as the sixth Governor of the Territory of Arizona. |
| 1881 | March 10 | The Territory of Arizona creates Graham County from portions of Apache County and Pima County. |
| 1881 | February 8 | The Territory of Arizona creates Gila County from portions of Maricopa County and Pinal County. |
| 1881 | February 1 | The Territory of Arizona creates Cochise County from a portion of Pima County. |
| 1880 | April 1 | The 1880 United States Census enumerates the population of the Territory of Arizona, later determined to be 40,440, an increase of 418.7% since the 1870 United States Census. Arizona becomes the fifth most populous of the eight U.S. territories. |

## 1870s

| Year | Date | Event |
| 1879 | February 24 | The Territory of Arizona creates Apache County from a portion of Yavapai County. |
| 1878 | October 6 | U.S. President Rutherford B. Hayes appoints John C. Frémont as the fifth Governor of the Territory of Arizona. |
| 1877 | July 9 | U.S. President Rutherford B. Hayes appoints John Philo Hoyt as the fourth Governor of the Territory of Arizona. |
| 1875 | February 1 | The Territory of Arizona creates Pinal County from portions of Maricopa County and Pima County. |
| 1871 | February 18 | The Territory of Arizona abolishes Pah-Ute County and annexes the remainder of the county in the Territory of Arizona to Mohave County. |
| 1871 | February 14 | The Territory of Arizona creates Maricopa County from portions of Pima County and Yavapai County. |
| 1870 | April 1 | The 1870 United States Census enumerates the population of the Territory of Arizona, later determined to be 9,658. Arizona becomes the eighth most populous of the nine U.S. territories. |

## 1860s

| Year | Date | Event |
| 1869 | July 9 | U.S. President Ulysses S. Grant appoints Anson P.K. Safford as the third Governor of the Territory of Arizona. |
| 1867 | January 18 | The State of Nevada accepts the portion the Territory of Arizona lying west of the 37th meridian west from Washington and the River Colorado of the West. The boundaries of the Territory of Arizona are now the same as the future State of Arizona. |
| 1866 | July 9 | U.S. President Andrew Johnson appoints Richard Cunningham McCormick as the second Governor of the Territory of Arizona. |
| 1865 | December 22 | The Territory of Arizona creates Pah-Ute County from a portion of Mohave County. |
| 1865 | May 9 | U.S. President Andrew Johnson proclaims the end of the American Civil War. |
| 1864 | November 9 | The Territory of Arizona creates four original counties: Mohave County, Pima County, Yavapai County, and Yuma County. |
| 1863 |
| 1863 | December 29 | U.S. President Abraham Lincoln appoints John Noble Goodwin as the first Governor of the Territory of Arizona. |
| 1863 | February 24 | U.S. President Abraham Lincoln signs An Act to provide a temporary Government for the Territory of Arizona, and for other Purposes. The act creates the Territory of Arizona from the portion of the Territory of New Mexico lying west of the 32nd meridian west from Washington (109°02′42.6″W). The Territory of Arizona includes all of the future State of Arizona plus the portion of the present-day State of Nevada lying south of the 37th parallel north. |
| 1862 | July 27 | The United States Army establishes Fort Bowie near Apache Pass. |
| 1862 | July | Texas cavalry retreat to Texas |
| 1862 | June 19 | U.S. President Abraham Lincoln signs An Act to secure Freedom to all Persons within the Territories of the United States, granting freedom to the slaves in all U.S. territories. |
| 1862 | April 15 | California cavalry engage Texas cavalry in the Battle of Picacho Pass, the westernmost battle of the American Civil War. |
| 1862 | February 28 | Texas cavalry occupy Tucson. |
| 1862 | February 24 | Confederate President Jefferson Davis proclaims that the portion of the Territory of New Mexico lying south of the 34th parallel north is the Confederate Territory of Arizona. |
| 1862 | February | The California Column departs Fort Yuma and advances into the Territory of New Mexico. |
| 1861 | July 25 | Texas cavalry under the command of Lieutenant Colonel John R. Baylor invades the Territory of New Mexico and occupies the town of Mesilla. |
| 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 | February 28 | U.S. President James Buchanan signs An Act to provide a temporary Government for the Territory of Colorado, creating the free Territory of Colorado. The Territory of Colorado annexes the portion of the Territory of New Mexico lying north of the 37th parallel north. The Territory of New Mexico now includes all of the future states of Arizona and New Mexico plus the portion of the present-day State of Nevada lying south of the 37th parallel north. |
| 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 | April 1 | The 1860 United States Census enumerates the population of the Territory of New Mexico, later determined to be 93,516, an increase of 51.9 since the 1850 United States Census. New Mexico becomes the second most populous of the seven U.S. territories. |

## 1850s

| Year | Date | Event |
| 1858 | September | The Overland Mail Company makes Tucson its 3rd division headquarters. |
| 1857 | August | The San Antonio–San Diego Mail Line reaches Tucson. |
| 1854 | June 8 | The Gadsden Purchase goes into effect creating the current United States-Mexico border. The Territory of New Mexico now includes all of the future states of Arizona and New Mexico plus portions of the present-day states Nevada and Colorado. |
| 1852 | January 9 | The Territory of New Mexico creates nine original counties: Bernalillo County, Doña Ana County, Rio Arriba County, San Miguel County, Santa Ana County, Santa Fe County, Socorro County, Taos County, and Valencia County. Doña Ana County and Socorro County extend into the future State of Arizona. Rio Arriba County, Santa Ana County, and Valencia County extend into the future states of Arizona and Nevada. Taos County extends into the future states of Arizona, Colorado, and Nevada |
| 1851 | September 18 | Colonel Edwin Vose Sumner establishes Fort Defiance, the first United States establishment in the future State of Arizona. |
| 1851 | April 5 | The State of Deseret dissolves. |
| 1850 | September 9 | The Territory of New Mexico and the Territory of Utah are established as part of the Compromise of 1850. U.S. President Millard Fillmore signs An Act proposing to the State of Texas the Establishment of her Northern and Western Boundaries, the Relinquishment by the said State of all Territory claimed by her exterior to said Boundaries, and of all her Claims upon the United States, and to establish a territorial Government for New Mexico. The Territory of New Mexico includes all of the future states of Arizona and New Mexico except the portion that shall be added by the Gadsden Purchase, plus portions of the present-day states of Colorado and Nevada. |
| 1850 | June 20 | In a failed attempt to organize a slave State of New Mexico, a state constitution is adopted by a vote of 6,771 to 39 and Henry Connelly is elected governor. U.S. military and civilian governor John Munroe refuses to let those elected take office without the express approval of the United States Congress. |
| 1850 | April 1 | The 1850 United States Census makes the first enumeration of the population of the future Territory of New Mexico, later determined to be 61,547. |

## 1840s

| Year | Date | Event |
| 1849 | March 12 | The Mormon settlers of the Great Salt Lake Valley create the Provisional Government of the State of Deseret and elect Brigham Young as the first (and only) Governor. The proposed state includes the entire Great Basin and the entire drainage basin of the Colorado River within the United States. Although the proposed State of Deseret includes most of the future State of Arizona, it has no actual presence in the region. |
| 1848 | February 2 | The United States and United Mexican States sign the Treaty of Guadalupe Hidalgo to end the Mexican–American War. Mexico relinquishes its northern territories. All land in the future State of Arizona north of the Mexican border becomes unorganized United States territory. |
| 1846 | September 22 | The Mormon Battalion under the command of Lieutenant Colonel Philip St. George Cooke occupies Tucson, Sonora. |
| 1846 | September 22 | Brigadier General Stephen W. Kearny appoints Charles Bent as the first U.S. civilian governor of New Mexico. |
| 1846 | August 22 | Brigadier General Stephen W. Kearny assumes command as the first U.S. military governor of New Mexico. |
| 1846 | August 18 | Troops under the command of General Stephen W. Kearny seize Santa Fe for the United States with little resistance. |
| 1846 | August 15 | U.S. Army troops under the command of Brigadier General Stephen W. Kearny enter Las Vegas, New Mexico. General Kearny proclaims that all of New Mexico is now under United States rule. |
| 1846 | May 13 | The United States declares war on the Mexican Republic. |

## 1820s

| Year | Date | Event |
| 1821 | August 24 | Ferdinand VII of Spain signs the Treaty of Córdoba recognizing the independence of the Mexican Empire. |

## 1810s

| Year | Date | Event |
| 1810 | August 1 | Mexican priest Miguel Gregorio Antonio Ignacio Hidalgo-Costilla y Gallaga Mandarte Villaseñor (Hidalgo) proclaims the independence of Mexico from the Napoleonic Kingdom of Spain in the village of Dolores. |

## 1790s

| Year | Date | Event |

## 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 29 | A Spanish-Franciscan expedition led by Franciscan priests Francisco Atanasio Domínguez and Silvestre Vélez de Escalante sets out from La Villa Real de la Santa Fé de San Francisco de Asís (Santa Fe) in search of an overland route to the Presidio Reál de San Carlos de Monterey (Monterey). The expedition follows the 1765 route of Juan Rivera northwest across the Colorado Plateau. The expedition fails to reach Las Californias, but reaches the lower Paria River in the future State of Arizona before returning to Santa Fe. |
| 1776 | July 4 | Representatives of the thirteen United States of America sign the Declaration of Independence from the Kingdom of Great Britain. |

## 1690s

| Year | Date | Event |

## 1590s

| Year | Date | Event |
| 1598 | July 12 | Don Juan de Oñate y Salazar establishes the Virreinato de Nueva España colony of Santa Fe de Nuevo Méjico at the village of San Juan de los Caballeros adjacent to the Ohkay Owingeh Pueblo at the confluence of the Rio Grande and the Río Chama. |

## 1540s

| Year | Date | Event |
| 1540 | July 7 | The military expedition led by Francisco Vásquez de Coronado, reaches the Zuni pueblo of Hawikuh. The Zuni resist but are driven off by the Spanish soldiers. Fray Marcos de Niza returns to Compostela in disgrace. |
| 1540 | February 23 | Francisco Vásquez de Coronado, Governor of Nueva Galicia, departs Compostela, México commanding a Spanish military expedition of 400 soldiers, 1,300 to 2,000 Mexican Indian allies, four Franciscan friars including Marcos de Niza and Juan de Padilla, and several slaves. |

## 1530s

| Year | Date | Event |
| 1539 | September | Fray Marcos de Niza returns to San Miguel de Culiacán after a distant view of the Zuni pueblo of Hawikuh. His glowing reports of Hawikuh inspire the 1540-1542 expedition of Francisco Vásquez de Coronado. |
| 1539 | March | Mustafa Azemmouri (Estevanico) leaves San Miguel de Culiacán followed by Fray Marcos de Niza in search of the Seven Cities of Cibola. Mustafa Azemmouri becomes the first African and Marcos de Niza becomes the first European to visit the future State of Arizona. Mustafa Azemmouri is murdered at the Zuni pueblo of Hawikuh. |
| 1536 | July | The four survivors of the Narváez expedition of 1527 arrive in Mexico City. Reports of their travels inspire stories of the Seven Cities of Cibola. |
| 1535 | | The four survivors of the Narváez expedition of 1527: Álvar Núñez Cabeza de Vaca, Andrés Dorantes de Carranza, Alonso del Castillo Maldonado, and Mustafa Azemmouri (slave name: Estevanico), may have traveled through the southern portion of the future State of Arizona. |

## 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 all of the future State of Arizona. |

## 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 along the Rocky Mountains to migrate throughout the Americas. |