FARGO-The Fargo-Moorhead metro area last year posted its most modest population gain in four years but still maintained steady growth even as North Dakota's go-go economy lost steam.

Fargo-Moorhead's population last year reached 238,124, an increase of 4,482 over 2015, or 1.9 percent, according to the latest estimates from the U.S. Census Bureau. By comparison, the metro area gained 5,220 residents the year before, in 2015.

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Most of the increase was in Cass County, which saw population growth of 3,725-more than three times the 1,117 residents North Dakota gained overall last year, according to the estimates. Clay County grew by 757.

"It's certainly not the growth we've seen in previous years," said Kevin Iverson, manager of the North Dakota Census Office. Still, he added, "All three metro areas grew," a reference to Fargo-Moorhead, Bismarck-Mandan and Grand Forks-East Grand Forks.

The F-M metro area, consisting of Cass and Clay counties, grew by 4,588 in 2014 and 6,584 in 2013, the largest increase since 2010. The metro area's average annual growth since 2010 is 4,192.

North Dakota's slower population growth reflects the slower economic growth, as the state's energy and agricultural sectors struggle during a prolonged price slump.

North Dakota's Oil Patch communities saw sharp population declines, reversing a trend of rapid growth fueled by the oil boom.

Three cities in or near the Bakken saw population losses: Williston lost 1,050 residents, or almost 3 percent; Minot decreased by 1,188, or 1.5 percent and Dickinson decreased by 940 residents, or 2.9 percent.

Three Oil Patch counties once soaring among the nation's fastest-growing, in percentage terms, during the peak of the boom several years ago plunged toward the bottom as they lost population last year.

McKenzie County, which includes Watford City, plummeted from the second-fastest growing county in 2015 to 2,858th. Williams County, which includes Williston, fell from third to 3,105th. Mountrail County, which includes Stanley, slid from sixth to 2,375th, according to Census Bureau rankings.

Despite the population losses in recent years, North Dakota's major Oil Patch counties still have populations that greatly exceed their 2010 levels, showing that they have managed to maintain much of the growth from the boom years, Iverson said.

Williams County's population is about 53 percent above 2010, while McKenzie County is about 98 percent higher and Stark County about 29 percent greater, he said.

"It's not like everybody left," Iverson added

Continuing a stubborn, decades-long trend of population erosion, aggravated in recent years by low farm commodity prices, many of North Dakota's rural counties declined, even outside the struggling Oil Patch.

In fact, Iverson said, North Dakota's modest growth last year was the result of the influx of young adults during the boom who stayed and had children. Births increased from 9,210 in 2011 to 11,824 last year, while deaths remained stable, between 6,000 and 6,200, he said.

"That's the sole reason we're seeing growth," Iverson said, noting North Dakota last year lost about 4,700 residents to out-migration, reversing a trend of significant in-migration driven by the oil boom, as workers flocked to the state, many earning six-figure paychecks.

The Oil Patch is showing some signs of a gradual rebound, but Iverson expects to see North Dakota's much more subdued growth trend continue, with an uptick possible.

"My gut tells me we may see more of the same, but not to the degree," he said.