The Cajun country of South Louisiana is one of many small regions interspersed throughout the U.S. where nearly everyone seems to have grown up nearby. In several rural parishes there, roughly 9 out of every 10 adults were born in the state. The local makeup elsewhere is far different, with as few as 1 in 10 adults born in-state in counties in Florida and Nevada.
These differences are largely a function of migration patterns, as Americans have gradually relocated to recently developed parts of the southern and western U.S. Much like native-born residents, those born abroad are also largely concentrated in relatively few states.
Sometimes a place may be home to a high concentration of natives because of its ability to retain residents, particularly younger adults. But more commonly, this concentration results from a failure to attract outsiders due to a lack of economic opportunity.
Nationally, about half of adults age 25 and older live in the state where they were born, according to the most recent American Community Survey data from the Census Bureau. We’ve mapped this data for all counties, showing where there are large concentrations of transplants or native-born residents.
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County Share of Age 25+ Population Born In-State
SOURCE: Governing calculations of 2017 five-year U.S. Census Bureau American Community Survey data
What Explains Homegrown Populations for Select Areas
California: About 64 percent of Californians native to the U.S. were born in the state. That’s higher than in most other states. But when the foreign born are factored in, particularly their large numbers in southern California, that statewide share drops to just 40 percent.
Clark County, Nev., and Mohave County, Ariz.: A mere 8 percent of adults in adjoining Clark and Mohave counties are natives, the least among counties in the contiguous U.S. Both attract steady streams of retirees, as well as Californians seeking a lower cost of living. The Las Vegas metro area’s population, comprising Clark County, was relatively small as recently as 30 years ago, but it’s been booming ever since. Mohave County, meanwhile, struggles to retain young adults, with no major universities and few job opportunities.
New Hampshire: New Hampshire is somewhat of an outlier in that only a third of its adults were born there, significantly less than in neighboring states. The southern border is very porous, with a large number of Massachusetts residents relocating to the Granite State, lured by less expensive housing and the absence of a sales or income tax. Net in-migration among older adults also remains positive as many residents of the Northeast who vacation in the state opt to retire there.
New York State: Excluding immigrants, about 77 percent of New York state’s adults began life in the state, among the highest concentrations nationally. Very few transplants, for instance, are found in the upstate counties surrounding Buffalo and Syracuse. New York City’s foreign-born population is so large, however, that it pushes the overall statewide proportion of in-state natives down considerably, with just over half of all residents over age 25 born in the state.
South Louisiana: Nearly three-quarters of Louisiana residents age 25 and up were born in the state, the highest share in the nation. Transplants are especially rare in South Louisiana outside the New Orleans area. In fact, the four county-level jurisdictions with the highest rates nationally are all rural South Louisiana parishes.
Westmoreland County, Pa.: Of all the larger, more populated counties in America, Westmoreland County, just east of Pittsburgh, ranks highest in its share of homegrown residents, with 86 percent of more than 260,000 adults born in-state. While Pittsburgh is growing its economy and retaining younger residents, Westmoreland struggles to do so, says Chris Briem, a University of Pittsburgh economist. Its population is aging, and some companies are exiting. One of the largest employers, a medical device manufacturer, announced last year it was moving to a mixed-use development in Pittsburgh.
One thing is certain: Illinois’ population has declined by 157,000 residents over the past five years, making it one of only two states — West Virginia is the other — to lose people over the past decade.