Arizona states of Sonora and Baja California. Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912, coinciding with Valentine's Day. 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. Southern Arizona is known for its desert climate, with very hot summers and mild winters.
Admission to the Union part of New York and was not admitted until New York consented); two large additions to Nevada, which became a state in 1864, were made in 1866 and 1867. However, there have been numerous minor adjustments to state boundaries over the years due to improved surveys, resolution of ambiguous or disputed boundary definitions, or minor mutually agreed boundary adjustments for administrative convenience or other purposes. One notable example is the case "New Jersey v. New York", in which New Jersey won roughly 90% of Ellis Island from New York in 1998. In addition to the original 13, six subsequent states