Mapping the Latino Population, By State, County and City by Anna Brown and Mark Hugo Lopez:

“The nation’s Hispanic population, while still anchored in its traditional settlement areas, continues to disperse across the U.S., according to a Pew Research Center analysis of U.S. Census Bureau data. Today, the 100 largest counties by Hispanic population contain 71% of all Hispanics. Los Angeles County, CA alone contains 4.9 million Hispanics, or 9% of the nation’s Hispanic population. But the share of all Hispanics who live in these same counties has fallen from 75% in 2000 and 78% in 1990 (Fry, 2008), reflecting Hispanic population growth outside of these 100 counties.”