Title: Territorial evolution of the United States
Content:  over the region was made to Panama in 1999. Regarding internal borders, while territories could shift wildly in size, once established states have generally retained their initial borders. Only four states—Maine, Kentucky, Vermont, and West Virginia—have been created from land claimed by another state; all of the others were created from territories or directly from acquisitions. Four states—Louisiana, Missouri, Nevada, and Pennsylvania—have expanded significantly by acquiring additional federal territory after their initial admission to the Union. The last state of the contiguous United States, commonly called the "lower 48", was admitted in 1912; the fiftieth and most recent state was admitted in 1959.
Title: 1912 in the United States
Content: February 14 &ndash; Arizona is admitted as the 48th U.S. state and the last of contiguous states to be admitted into the Union (see History of Arizona). 
Title: Southwestern United States
Content:  mining industry in the region. In 1901, the Santa Fe Railroad reached the South Rim of the Grand Canyon, opening the way for a tourism boom, a trend led by restaurant and hotel entrepreneur Fred Harvey. The last two territories within the Southwest to achieve statehood were New Mexico and Arizona. By 1863, with the splitting off of the Arizona Territory, New Mexico reached its modern borders. They became states within forty days of one another. On January 6, 1912, New Mexico became the 47th state in the Union. Arizona would shortly follow, becoming the last of the 48 contiguous United States on February 14, 1912.
Title: Twilight's Last Gleaming (novel)
Content:  the budget with tax revenues a tiny fraction of what they had been before the war. It is too little, too late, however; numerous states begin to ratify the dissolution amendment, starting with South Carolina. In January 2027, Nebraska becomes the thirty-eighth state to ratify, and the United States of America officially ceases to exist. In the following weeks, the states begin to arrange themselves into a number of successor states. In Washington, Bridgeport and other former government officials contemplate founding a rump United States out of states that voted against ratification, based in the Rust Belt and Mid-Atlantic regions.
Title: 1788 in the United States
Content:  ; May 23 &ndash; South Carolina ratifies the United States Constitution and becomes the 8th U.S. state (see History of South Carolina). ; June 21 &ndash; New Hampshire ratifies the United States Constitution and becomes the 9th U.S. state (see History of New Hampshire), the Constitution goes into effect. ; June 25 &ndash; Virginia ratifies the United States Constitution and becomes the 10th U.S. state under the new government (see History of Virginia). ; July 26 &ndash; New York ratifies the United States Constitution and becomes the 11th U.S. state (see History of New York). ; November 15 &ndash; Cyrus Griffin resigns as President of the Continental Congress after only two delegates arrived for the final session. 
Title: 1788 in the United States
Content: January 2 &ndash; Georgia ratifies the United States Constitution and becomes the 4th U.S. state under the new government (see History of Georgia). ; January 9 &ndash; Connecticut ratifies the United States Constitution and becomes the 5th U.S. state (see History of Connecticut). ; January 22 &ndash; the Continental Congress, effectively a caretaker government, elects Cyrus Griffin as its last president. ; February 1 &ndash; Isaac Briggs and William Longstreet patent the steamboat in Georgia. ; February 6 &ndash; Massachusetts ratifies the United States Constitution and becomes the 6th U.S. state (see History of Massachusetts). ; March 21 &ndash; Great New Orleans Fire (1788) kills 25% of the population and destroys 856 buildings, including St. Louis Cathedral and 
Title: U.S. state
Content: California, 1850, from land ceded to the United States by Mexico in 1848 under the terms of the Treaty of Guadalupe Hidalgo. ; Kentucky, 1792, from Virginia (District of Kentucky: Fayette, Jefferson, and Lincoln counties) ; Maine, 1820, from Massachusetts (District of Maine) ; Texas, 1845, previously the Republic of Texas ; Vermont, 1791, previously the Vermont Republic (also known as the New Hampshire Grants and claimed by New York) ; West Virginia, 1863, from Virginia (Trans-Allegheny region counties) during the Civil War  Article IV also grants to Congress the authority to admit new states into the Union. Since the establishment of the United States in 1776, the number of states has 
Title: State governments of the United States
Content:  formed from organized territories established and governed by Congress in accord with its plenary power under Article IV, Section 3, Clause 2 of the Constitution. Six subsequent states were never an organized territory of the federal government, or part of one, before being admitted to the Union. Three were set off from an already existing state: Kentucky (1792, from Virginia),  Maine (1820, from Massachusetts),   and West Virginia (1863, from Virginia). Two were sovereign states at the time of their admission: Texas (1845, previously the Republic of Texas), and Vermont (1791, previously the De facto but unrecognized Vermont Republic). One was established from unorganized territory: California (1850, from land ceded to the United States by Mexico in 1848 under the terms of the Treaty of Guadalupe Hidalgo).
Title: Admission to the Union
Content:  United States by Mexico in the 1848 Treaty of Guadalupe Hidalgo at the end of the Mexican–American War. The Act of Congress establishing California as the 31st state was part of the Compromise of 1850. ; West Virginia, admitted June 20, 1863, during the Civil War, was set off from Virginia (previously its northwestern trans-Allegheny region). The General Assembly of the Restored Government of Virginia passed an act on May 13, 1862, granting permission for the creation of West Virginia. Later, by its ruling in Virginia v. West Virginia (1871), the Supreme Court implicitly affirmed that the breakaway Virginia counties did have the proper consents required to become a separate state.  In addition to the original 13, six subsequent states were never part of an organized incorporated U.S. territory:
Title: Outline of United States history
Content:  Commonwealth of Pennsylvania becomes the 2nd state to ratify the US Constitution on December 12, 1787 ; The State of New Jersey becomes the 3rd state to ratify the US Constitution on December 18, 1787 ; The State of Georgia becomes the 4th state to ratify the US Constitution on January 2, 1788 ; The State of Connecticut becomes the 5th state to ratify the US Constitution on January 9, 1788 ; The Commonwealth of Massachusetts becomes the 6th state to ratify the US Constitution on February 6, 1788 ; The State of Maryland becomes the 7th state to ratify the US Constitution on April 28, 1788 ; The State of South Carolina becomes the 8th state to 

Question: when did the last state became a state?
Answer: Hawaii.
August 21, 1959.