The history of Latinos and Hispanics in the United States is wide-ranging, spanning more than four hundred years and varying from region to region within the United States. The Latino and/or Hispanic presence in the United States is the second longest, after the Native American.

Contemporaneously with their explorations and conquests elsewhere in America, most famously those of Hernan Cortes in Mexico and Francisco Pizarro in Peru, Spaniards pioneered the present-day United States, too. Hispanics (whether criollo or mestizo) became the first American citizens in the newly acquired Southwest territory after the Mexican-American War, and remained a majority in several states until the 20th century.

As late as 1783, at the end of the American Revolutionary War, Spain held claim to roughly half of today's continental United States. In the Treaty of Paris, France ceded Louisiana (New France) to Spain from 1763 until it was returned in 1800 by the Treaty of San Ildefonso. In 1775, Spanish ships reached Alaska. From 1819 to 1848, the United States and its army increased the nation's area by roughly a third at Spanish and Mexican expense, gaining among others three of today's four most populous states: California, Texas, and Florida.