Downtown Washington is seen from the roof of a building near the National Cathedral in this file photo. (Toni L. Sandys/The Washington Post)

The Washington region is in the midst of a striking slowdown in its growth rate as it draws far fewer residents from elsewhere in the country than in previous years.

The region had a net influx of about 4,500 people from around the United States between July 2012 and July 2013, according to recently released census figures analyzed by William Frey, a demographer with the Brookings Institution. That reflects a slump to less than one-fifth of what it was just two years earlier.

Though the region of 6 million people grew by about 87,000 residents over the one-year span, more than half of that, 50,000, was due to births outpacing deaths, Frey’s analysis showed.

The census figures reflect a region whose growth is decelerating after high growth in most of the previous decade, driven by federal spending after the terrorist attacks of Sept. 11, 2001, and fueled further during the recession when few other places in the country had jobs.

Now, the growth is moderating. The region’s growth rate has slowed by more than a quarter in just three years, from over 2 percent in 2010 to 1.5 percent last year, according to Frey’s analysis. Officials say federal budget cuts are the major reason.

“We’re at a pause, where it’s unclear how much the federal presence will be evolving because of budget constraints, pressures on federal spending and reductions in federal civilian employment in different agencies,” said Paul DesJardin, director of planning for the Metropolitan Washington Council of Governments. “But we’re still growing as a region and doing much better than so many other parts of the country. Coming after a period of such unprecedented growth, we’re catching our breaths.”

Job growth in and around Washington has changed considerably in the past two years. Most of the new jobs have been in work that tends to have lower to moderate wages, including food service, health, education and retail, said Stephen Fuller, director of the Center for Regional Analysis at George Mason University. But federal jobs, which account for a third of all employment in the Washington region and carry some of the highest salaries, actually shrank, he said. That in turn has lessened the region’s attraction as a job magnet.

“The incentive to come to Washington has worn down,” Fuller said. “It’s taken a bit of air out of our balloon.”

Citing more robust economies in Texas, Boston, Atlanta, New York and Los Angeles, Fuller added, “We’re a step ahead of Detroit.”

The region’s relative ranking compared with other large cities underscores why the drop-off in newcomers from other parts of the country is having such an outsized impact on growth in Washington.

Among the 100 largest metropolitan regions, Washington ranks fifth in the overall number of new residents, after Houston, New York, Dallas and Los Angeles. In the number of immigrants from other countries, it ranks fourth, behind New York, Miami and Los Angeles.

But in the number of newcomers from elsewhere in the country, the Washington area ranks 28th. Just two years earlier, it was fifth.

As the region’s growth has become more dependent on natural increase, which is the difference between births and deaths, the Washington region is beginning to resemble cities that either have a lot of young immigrants, or a lot of Mormons. Only 10 other metro regions in the country had higher rates of natural increase, all in Utah, Texas and California.

Within the region, of course, there are significant differences. In the past two years, there has been the District and then there’s almost everywhere else.

Six jurisdictions, including the region’s biggest counties of Montgomery, Fairfax and Prince George’s, showed net declines in what demographers call domestic migration, or the influx of residents from elsewhere within the country. The six jurisdictions all registered population increases, but the gains were driven almost entirely by births instead of new residents moving in.

The District, however, stood out among its neighbors. It gained 13,000 residents over the year, driving the population to over 646,000, according to the census figures. That was more new residents than any other jurisdiction in the region. Loudoun County also gained population, almost as much as the District.

More significantly, births were not the only reason the District had population gains. Last year, as in each of the previous three years, the city got more than 6,000 newcomers from outside the District, and almost 3,000 from other countries.

Frey called the District the region’s demographic bright spot.

“While the region as a whole is attracting fewer migrants from the rest of the country and is reliant largely on immigration and fertility for growth,” he said, “the primary source of growth in the District is migration from the suburbs and beyond. D.C. continues to remain demographically healthy despite ups and downs in the rest of the region.”