Dallas, Johnson counties fastest growing in Iowa, U.S. Census data shows

Urban shift continues, as rural population declines

A North Liberty neighborhood in an aerial photograph in North Liberty on Wednesday, May 14, 2014. (The Gazette file photo)
A North Liberty neighborhood in an aerial photograph in North Liberty on Wednesday, May 14, 2014. (The Gazette file photo)

CEDAR RAPIDS — Johnson County is the second fastest-growing county in Iowa behind Dallas County, home to Waukee on the outskirts of the Des Moines metro area, according to the latest U.S. Census Bureau figures released Thursday by the State Data Center.

The population in Dallas, which ranked as the eighth fastest-growing county nationwide since 2010, has climbed more than 36 percent, or 24,042, to 90,180 people.

Johnson, home to growing suburbs of Tiffin and North Liberty, had a 15.6 percent increase in population to 151,260 people as of July 1, 2018.

“It’s hard to know for sure what areas contributed to county growth based on the data released today,” said Gary Krob, State Data Center coordinator. “In Polk County, it’s not just the Des Moines area that is growing but neighboring communities. Places like Johnson County, I would suspect will show Tiffin and North Liberty are some of the bigger contributors to growth.”

The latest numbers reinforce the trend of an urban shift.

Only 30 of the state’s 99 counties are growing while 69 have lost population since 2010. The state as a whole has grown by 109,273 people, or 3.6 percent, to 3,156,145.

“We tend to see when we look at migration patterns a lot of movement between counties and some loss out of state, but a lot of it is population moving out of rural areas moving closer to urban areas, although not necessarily to the center of the urban area,” Krob said.

Much of the growth in Iowa is in or adjacent to metropolitan areas, which could explain growth in communities surrounding metropolitan centers.


More than half the state’s population lives in 10 counties — Polk, Linn, Scott, Johnson, Black Hawk, Woodbury, Story, Dubuque, Pottawattamie and Dallas.

Polk followed Dallas and Johnson counties by adding 56,572 people — the largest numerical increase statewide — or 13.1 percent since 2010, to 487,204 people.

Linn County added 14,671 people, a 6.9 percent increase, bringing the total population to 225,909, which ranked it as the seventh-fastest growing county in the state.

The Des Moines-West Des Moines metro area was the fastest-growing metropolitan statistical area in Iowa since 2010 with a growth of 15.1 percent, followed by the Iowa City metro area at 13.6 percent and the Ames metro area at 9.6 percent growth.

Clinton County has declined the most since 2010, losing 2,599 people, while Emmet County declined at the fastest rate, losing 10.2 percent of its population.

The population changes are based on the 2010 census and estimates as of July 1, 2018. More in-depth estimates of cities and demographic information, such as gender, race and ethnicity, are expected to be released in June, Krob said, citing Census Bureau information.

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