In 1513 the Spanish explorer, Ponce De Leon discovered Florida. Five years later another captain from Spain, Cabeza de Vaca, led a small party that explored parts of Texas, New Mexico and Arizona. Other Spanish adventurers who made important discoveries included Francisco Coronado who traveled up the Colorado River (1540) and Hernando de Soto who explored the Mississippi River (1541).

In the 16th century Spain took control of Florida, California and the south-west region of America. About 200,000 Spaniards migrated to the new world and founded some 200 settlements in the Americas. St. Augustine, Florida, founded by Pedro Merendez in 1565, was the first permanent settlement established by Europeans in what is now the United States. Other important settlement established by the Spanish in America included Sante Fe, Albuquerque, El Paso, San Diego, San Francisco, Santa Barbara, San Jose, Monterey, and Los Angeles. The Spanish mined precious metals and was able to ship back to Europe large quantities of gold and silver.

In 1810 the United States annexed West Florida. Three years later the Americans seized the area around Mobile. When Seminoes based in Florid began raiding American settlements in 1817, Spain was warned that it must either police her territory properly or grant it to the United States. Unable to spare troops desperately needed to hold onto her Latin American colonies, Spain agreed to sell Florida in 1819 to the United States for $5 million.

By 1846 there were about 8,000 Spaniards living in California. There was an estimated 500 Americans but this changed when gold was discovered in January, 1848 on land owned by John Sutter in California. News soon spread about the discovery and by 1849 over 100,000 people had arrived in search of gold. The Americans who now clearly outnumbered the Spaniards, organized a government and in 1850 California was admitted as the 31st state of the Union. After it lost all its territory in America, emigration from Spain was negligible.