The Portland area’s mid-decade growth spurt has slowed dramatically, new census numbers suggest.

Population estimates from the U.S. Census Bureau show the metro area’s population growth rate for 2018 was just 0.9%, or about 430 new residents a week — half what it was in 2016.

As a result, Portland has plummeted down the list of fastest-growing large metro areas, from 24th in 2016 to 42nd last year among the largest 100 metros. Growth has slowed in each of the area’s largest counties, but the numbers suggest the slowdown is more acute in the population center of Multnomah County.

The bureau pegs the population for the Portland metro — which includes Multnomah, Washington, Clackamas, Columbia and Yamhill counties in Oregon and Clark and Skamania counties in Washington state — at 2,478,810.

Population estimates aren’t an exact science. Unlike the every-10-years census, which endeavors to account for every single U.S. resident through surveys and interviews, annual population estimates are extrapolated from data like birth and death records, tax returns, home construction permits and school enrollment.

Charles Rynerson, a faculty member of the Population Research Center at Portland State University, said the Census Bureau’s estimates look a little low for the metro area.

But the center’s own estimates agree that the region isn’t growing as fast as it once was.

Slower population growth is not unexpected.

Economists have said the region’s economy is essentially maxed out, which has slowed hiring and resulted in fewer people moving to Oregon for work. Migration is the state’s primary source of new residents.

“There’s been a little bit less employment growth,” Rynerson said. “We’re relying on net migration for most of our growth, and net migration relies on employment growth.”

The other source of growth, births offset by deaths, is relatively low across the nation. That’s a source of concern for economists, who say a smaller labor pool can stymie economic growth in the long run.

Portland’s effectively competing for workers with other metro areas, said John Tapogna, the president of the economics firm ECONorthwest. Rising housing costs and an erosion of middle-income jobs could slow the region’s economic engine.

“To the extent that we mismanage our housing policy and allow housing prices to rise, to the extent that we aren’t able to manage our fiscal affairs in a way that supports well-respected educational and other public services, we’ll be on the losing end of that fight,” Tapogna said.

Still, Portland’s growth remains strong by historical standards. It’s gained an average of 30,000 people per year over the past two decades, a level exceeded only by the even more rapid growth of the 1990s.

Other parts of the state are still seeing rapid population growth.

Crook County, whose biggest city is Prineville, is the state’s fastest-growing county. Nationwide, it’s the 38th fastest-growing county with a population of more than 10,000.

It’s seen spillover growth from nearby Deschutes County — the state’s second fastest-growing county, where rising rents and home prices in Bend have pushed out lower-income residents.

But it’s also seen spillover business growth, as well as some homegrown industries, including a boom in datacenters and solar power farms.

That’s brought in construction jobs, as well as maintenance work that’s coming close to exceeding the wood products industry that had long been the economic powerhouse of central Oregon, said Roger Lee, the chief executive of the economic development group EDCO.

Crook County had lagged the growth in Deschutes County, Lee said, but it’s now coming into its own as an economic center.

“Bend kind of had this cool factor,” Lee said. “The place itself was driving the population growth and not people coming here for a job opportunity. That’s a little different from what’s happening in Crook County. People are coming for the opportunity.”

-- Elliot Njus

enjus@oregonian.com; 503-294-5034; @enjus

Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.