© The Associated Press Apartment buildings under construction in the Orlando, Florida, suburb of Maitland. More people are moving to Sun Belt states such as Florida, now that the economy has improved.

Americans are heading South and West again in search of jobs and more affordable housing, as the nation’s economic health continues to improve.

Census population estimates show that the 16 states and the District of Columbia that comprise the South saw an increase of almost 1.4 million people between 2014 and 2015. The 13 states in the West grew by about 866,000 people.

The gains represent the largest annual growth in population of the decade for both regions and signal that the multi-decade migration to the Sun Belt has resumed after being interrupted by the Great Recession of 2007-09 and the economic sluggishness and anxiety that followed.

In comparison, population growth in the Northeast and the Midwest — including what’s known as the Snow Belt — remained sluggish, growing by about 258,000 residents combined.

“Clearly, the Snow Belt-to-Sun Belt migration is coming back after a huge lull in response to the recession and post-recession period,” said demographer William Frey, of the Brookings Institution. “Up until now, regional migration was not picking up at the same time that other economic indicators — jobs and housing — seemed to be on the upswing.”

The numbers indicate Americans’ growing willingness to pick up and go after having sat still earlier in the economically tenuous decade, when the U.S. Census Bureau reported that only one in five people who wanted to move somewhere else did so.

The new estimates, released last month, arrive midway through the decade, halfway to the next census, in 2020, and provide some indications of where the nation is headed from the standpoint of governing from Washington.

If the population shift continues, Texas could gain three new seats in the U.S. House, Florida two, and Arizona, Colorado, North Carolina and Oregon one apiece after the next census, according to an analysis by Election Data Services, a political consulting firm based in Virginia.

Nine states — Alabama, Illinois, Michigan, Minnesota, New York, Ohio, Pennsylvania, Rhode Island and West Virginia — could meanwhile lose a seat apiece.

Economic Reasons Drive the Moving

The shift in population reflects the economic conditions many Americans experience or aspire to.

A search for jobs and more affordable housing were behind two-thirds of the long-distance moves made between 2014 and 2015, according to a separate census report. Family reasons, such as getting married or rejoining relatives, accounted for another quarter of households moving.

Texas, for example — which had the biggest population gain from 2014 to 2015, an increase of 490,000 people for a total 27,469,114 — is a magnet for job-seekers from elsewhere. It has been at the fore in high job growth and outpaced the nation’s economic growth since the recession.

Other Sun Belt states that witnessed a growth in population — such as Georgia and Nevada — also had some of the largest increases in job growth or economic output, as did Colorado, Oregon and Utah.

West Virginia, meanwhile, suffered a population loss of almost 5,000. The state, which has relied economically on a declining coal industry, has higher unemployment and lower job growth rates than the national average — giving more people more reasons to leave.

“As long as the state economy continues to stall, population loss will likely continue as well,” said Christiadi, a demographer at West Virginia University.

Six other states also had population losses for the year: Connecticut, Illinois, Maine, Mississippi, New Mexico and Vermont. And like West Virginia, many are struggling to provide economic opportunity. New Mexico, Connecticut and Maine had some of the lowest rates of job creation in recent years.

Florida’s gain of almost 366,000 people to a population of 20,271,272 was its largest in a decade and reflects another cause behind the renewed exodus to the Sun Belt: The nation’s swollen population of baby boomers now feels more secure economically in picking up and moving to traditional retirement oases.

“The state continues to attract retiring baby boomers because of our climate and the relatively low costs of living,” said Richard Doty, a demographer with the University of Florida’s Bureau of Economic and Business Research. “You can sell a home in New York or Ohio or Michigan for substantially more than you would spend in Florida, so it’s still relatively attractive.”

Take, for example, Sumter County, west of Orlando, one of Florida’s fastest-growing counties, driven in large part by retirees. It is projected to have a median age of 78 by 2020, Doty said.

A typical Sumter County home costs about $224,000 — or about half the price of a home in a New York City suburb, such as Long Island’s Nassau County.

Population Shifts Inside States

The influx and exodus of people has ramifications for local housing, tax bases and governments — even within state boundaries.

In Oregon, where the economy is partly being driven by chip manufacturing for firms like Intel, young people are moving to Portland, said Josh Lehner, an economist at the state’s Department of Economic Analysis. That’s creating a housing shortage, as construction fails to keep up with demand.

Many of Oregon’s newcomers are from neighboring California, which had more than 77,000 people move out. That’s more than twice the number who left between 2013 and 2014. The state showed a net increase in population in 2014-15 of more than 350,000 only as a result of births and new immigrants.

Many left because of housing costs. A typical home in California costs two-thirds more than in Oregon, for example.

The cost of housing can limit the number of people willing to move into California to take even high-paying, high-tech jobs in places like San Francisco, said John Malson, chief of demographic research at the California Department of Finance.

“You have a very good job market here in tech, so people who are coming here are coming for the attractive job opportunities,” Malson said. “But it’s very expensive to live in California.”

A state’s net population growth and loss numbers can sometimes cloud what’s going on within its boundaries, meaning that some job-rich urban areas might be flourishing but rural areas might not be.

Take Massachusetts, for example, the fastest-growing state in the Northeast.

Susan Strate, manager of population estimates at the University of Massachusetts Donahue Institute, said young people from other states and well-educated foreign immigrants are boosting the Boston area’s population by taking jobs in medicine, education and biotech.

Meanwhile, she said, “Some of the little towns are losing what few young people they have.”

Illinois, whose population dropped by 22,000 people to 12,859,995, is another state undergoing a similar trend.

Chicago is attracting more businesses and young, educated professionals to fill those jobs, while many less-expensive rural and suburban areas with less economic opportunity struggle, said Rob Paral, a Chicago demographic consultant.

Available jobs and a person’s ability to fill them, he said, are intertwined with population shifts — within the state, or to the Sun Belt.

“There are many high-skill jobs overall,” Paral said. “Jobs for lower-skill young persons are another story, combined with high housing costs: If you are going to make the same low wage in Illinois or in a Southwestern state, the latter offers cheaper housing and warmer weather.”