Arlington’s resident population grew 10.4 percent from the April 2010 census to July 2014, according to new estimates, placing its rate of growth second among the commonwealth’s counties.

The new figures from the University of Virginia’s Weldon Cooper Center for Public Service peg Arlington’s mid-2014 population at 229,302, an increase of 21,675 residents from the census figure reported four years earlier.

The highest rate of growth among counties was in Loudoun County, where the population increased an estimated 15.8 percent. Virginia’s largest jurisdiction, Fairfax County, posted a growth rate of 3.4 percent, while Prince William County grew at a rate of 8.9 percent.

Statewide, Virginia’s estimated population of 8.33 million in 2014 was up 325,000 people, or 4.1 percent, from 2010.

Based on updated population estimates, Virginia remains the nation’s 12th-largest state.

The Northern Virginia region saw its estimated population rise 7.1 percent to 2.87 million during the period. The population growth of the remainder of the commonwealth was estimated at just 2.5 percent.

“While the economy is recovering, population growth lags at the state and national levels,” said Qian Cai, director of the Cooper Center’s Demographics Research Group. “People are cautious about having babies, buying houses or making big moves.”

According to the data, nearly 87 percent of Virginians live within the boundaries of the commonwealth’s 10 metropolitan areas.

The complete demographic estimates are available on the Web site at www.coopercenter.org.