The population is growing in five cities across St. Charles County, while most other cities in the St. Louis region are down, according to the latest figures from the U.S. Census Bureau. 

“This shows people like what we’ve got here—safe neighborhoods, good schools and nice places to live,” says County Executive Steve Ehlmann. “And we’re working to keep it that way.”

From 2020-2025, the latest population estimates show growth in:

• O’Fallon, Mo., with 4,713 more people, up 5%
• Wentzville with 4,552 more people, up 10%
• St. Peters with 3,746 more people, up 6.4%
• Lake Saint Louis with 2,406 more people, up 14.3%
• St. Charles City with 1,925 more people, up 2.7%

Besides growth in those incorporated cities, the population is also rising countywide—including unincorporated St. Charles County. From 2020 to 2025, the county’s total population rose by more than 21,000 people. 

“There are certain limits to growth in St. Charles County,” Ehlmann says. “Forty-three percent of our land is in the floodplain, and probably another 10 or 15 percent is in the Femme Osage watershed, which is too hilly, rocky, to support subdivisions, but there are areas left in the county that can grow. It can have various densities, depending upon topography and the forestation around it, and we're going to continue the policies that brought these people here in the past and hope that we do continue to grow.”

St. Louis University demographer Dr. Ness Sandoval says St. Charles County still has momentum. 

“The great thing is you’re still building homes,” Sandoval says. “You want to keep the momentum going—population growth, housing growth. You don't want to stop it. You don't want to be in a place where you say, ‘I don't want it.’ I would not stop the momentum, because once it stops, it's very hard to restart.”

Sandoval says the best kind of population growth is young people with children. More census data is scheduled to be published in July showing the age of newcomers.

Meanwhile, St. Charles County Director of Community Development Mike Hurlbert says growth is not the only measure of success. 

“Smart planning weighs growth, while mindful of the costs to infrastructure, traffic, schools, and preserving the landscapes that make St. Charles County attractive to our continuing development,” Hurlbert says. 

Ehlmann says the County has been working for years to create roads that follow the growth—not anticipate where it will happen. 

“We don't build roads to show people where we think they should live,” Ehlmann says. “We wait to see where people want to live, and they definitely want to live in certain parts of our county, and we're busy now catching up to make sure that when those homes get built, that the roads would be sufficient to serve people living there.”

Declining most among cities in the region is the City of St. Louis, with 23,205 fewer people, down 7.7%.

But the population loss was also felt across many cities in the region:

• Belleville down 5%
• Collinsville down 2.8%
• Granite City down 2.7%
• Florissant down 2.6%
• Alton down 2.6%
• Maryland Heights down 2.6%
• Ballwin down 2.5%
• Hazelwood down 2.3%
• Webster Groves down 2.3%
• Creve Coeur down 1.8%
• Manchester down 1.4%
• Edwardsville down 1.4%
• Chesterfield down 1.3 %
• Wildwood down 1.3%
• Kirkwood down 0.45%

Apart from the five St. Charles County cities that were up, three other cities in the region also gained population:

• Clayton with 439 more people, up 2.5%
• O’Fallon, Ill., with 224 more people, up 0.69%
• Arnold with 97 more people, up 0.46