Many of the nation’s large urban centers have seen a slow, yet growing exodus of residents to more suburban areas in recent years. New county population estimates released by the Census Bureau on Thursday suggest this shift isn't slowing down.

Migration out of densely populated areas has broadened, now spanning highly educated urban counties and more regions of the country. Some jurisdictions, such as New York City’s boroughs, are seeing larger than typical losses to other localities. Even big counties experiencing population growth aren’t adding quite as many residents as before.

A review of the latest estimates finds that 125 large, predominately urban counties lost an aggregate net total of 377,000 residents from domestic migration last year, following declines of 225,000 in 2016 and 132,000 in 2015. Average migration rates similarly dropped for these counties, which we define as those containing the largest city in metro areas with populations exceeding a half million or any other city with more than 200,000 residents.

Domestic migration rates continued to decline in four of New York City’s five boroughs last year. Los Angeles County, Calif., has similarly seen its net domestic migration rate dip further each year since 2012, with a net total of just under 92,000 residents leaving last year.

One jurisdiction experiencing a particularly large uptick in outward migration was Miami-Dade County, Fla. Manny Armada, the county’s chief of planning research, attributes part of that to rising home values. Affordability concerns have likely pushed some families to relocate to less expensive areas of the state, while others who bought homes during the depths of the recession wanted to cash in.

“We’re basically witnessing the same pressures you see in all the cities across the country,” Armada says.

A further breakdown of the data suggests that several more educated jurisdictions were mostly spared from domestic migration losses until recently. Consider San Francisco County and Alameda County, Calif. Both highly educated counties have seen net domestic migration turn negative after years of gains. Last year, large urban counties where more than a third of adults hold at least a bachelor’s degree recorded an average net domestic migration of -17 per 1,000 residents -- a rate that had previously remained positive or flat.

Localities in thriving regions of the South are mostly continuing to grow. But this, too, is slowly changing. Aggregate domestic migration for 49 Southern large, more urban counties was essentially flat in 2017 after years of growth. Harris County, Texas, which includes Houston, was adding more residents than it lost until 2016; Census estimates suggest outmigration accelerated there last year.

Major urban counties in the Northeastern U.S. continue to sustain the largest migration losses, followed by those in the Midwest. Those out West have held up better. Clark County, Nev., and Maricopa County, Ariz., to name a couple, have yet to experience any drop-off in migration.

Perhaps the biggest determining factor in how these counties are doing is density. The nation’s most densely populated counties -- those with more than 1,000 residents per square mile -- have incurred steeper losses the past two years.

It's the counties that tend to be more suburban that are experiencing upticks in migration after slowing during the recession. Five such counties in Florida recorded among the highest domestic migration rates last year: Brevard County, Lee County, Polk County, Sarasota County and Volusia County. El Paso County, Colo., and Spokane, Wash., are two other similarly situated jurisdictions where growth hasn’t slowed down.

If there’s good news for some of the larger, more densely-populated counties, it’s that most continue to register gains in total population, albeit at a slower pace than before.

This is mostly a result of steady migration flows from abroad. Immigration to Miami-Dade County remains strong -- more than offsetting the county’s domestic migration losses. If it weren’t for international migration, many other urban counties and their cities would be experiencing overall population declines.

Data Definitions

Large Urban Counties: County-level jurisdictions either containing the largest city within metro areas of populations exceeding 500,000, or those encompassing any city with a population over 200,000. Includes the independent cities of Baltimore, Chesapeake, Va.; Norfolk, Va.; Richmond, Va.; St. Louis and Virginia Beach, Va. In all, approximately 134 million Americans live in these 125 counties.

Domestic Migration Rates: Figures represent net rates per 1,000 population.

Highly Educated Counties: Jurisdictions where more than one-third of adults age 25 and up hold at least a bachelor’s degree, per 2011-2016 Census American Community Survey estimates. A total of 55 large urban counties met this definition.

Regions: States classified using Census Bureau definitions.