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.
Although today the state's largest population center is around Chicago in the northeastern part of the state, the state's European population grew first in the west, with French Canadians who settled along the Mississippi River, and gave the area the name Illinois. After the American Revolutionary War established the United States, American settlers began arriving from Kentucky in the 1780s via the Ohio River, and the population grew from south to north. In 1818, Illinois achieved statehood. After construction of the Erie Canal increased traffic and trade through the Great Lakes, Chicago was founded in the 1830s on the banks of the Chicago River, at one of the few natural harbors on southern Lake Michigan.John Deere's invention of the self-scouring steel plow turned Illinois's rich prairie into some of the world's most productive and valuable farmland, attracting immigrant farmers from Germany and Sweden. The Illinois and Michigan Canal (1848) made transportation between the Great Lakes and the Mississippi River valley faster and cheaper. New railroads carried immigrants to new homes, as well as being used to ship commodity crops to Eastern markets. The state became a transportation hub for the nation.