Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912. Historically part of the territory of Alta California in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase.
West Virginia became a state following the Wheeling Conventions of 1861, after the American Civil War had begun. Delegates from some Unionist counties of northwestern Virginia decided to break away from Virginia, although they included many secessionist counties in the new state. West Virginia was admitted to the Union on June 20, 1863, and was a key border state during the war. West Virginia was the only state to form by separating from a Confederate state, the first to separate from any state since Maine separated from Massachusetts, and was one of two states admitted to the Union during the American Civil War (the other being Nevada). While a portion of its residents held slaves, most of the residents were yeomen farmers, and the delegates provided for gradual abolition of slavery in the new state constitution.