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.
Pennsylvania is the 33rd-largest, the 6th-most populous, and the 9th-most densely populated of the 50 United States. The state's five most populous cities are Philadelphia (1,560,297), Pittsburgh (305,801), Allentown (118,577), Erie (100,671), and Reading (89,893). The state capital, and its ninth-largest city, is Harrisburg. Pennsylvania has 140 miles (225 km) of shoreline along Lake Erie and the Delaware Estuary.