The City of Milwaukee's population declined by 4,366 people from 2015 to 2016, erasing much of the slow but steady gains the city experienced since 2010, according to figures released Thursday by the U.S. Census Bureau.

For the first part of the decade, the city saw slight annual population increases, growing from 595,188 in 2010 to 600,178 in 2014. Starting with the 2015 population estimates, Milwaukee's numbers started declining, falling by about 1% to 595,047 in 2016.

"I will review Milwaukee’s population estimates and those of other large cities, including Midwestern cities, keeping in mind these estimates are sometimes unreliable," Milwaukee Mayor Tom Barrett wrote in a statement, saying also that the 2016 estimate is still higher than the 2010 April census count of 594,833.

"Keep in mind that the 2020 decennial count is what matters the most and not the 2016 estimate. I’m confident Milwaukee will fare well in 2020," he wrote. "Bottom line, Milwaukee is not a city in rapid decline because its population is leaving. I’m confident that the 2020 final count will prove it."

DATABASE:Population estimates for cities, towns and villages 2010 - 2016

The Census Bureau produces population estimates for the nation, states, counties, and cities, towns and villages on an annual basis. The estimates are from July 1 each year, while the decennial census is an April 1 count.

The trend in Milwaukee was one that manifested across the Rust Belt. Chicago's population declined by 8,638 to 2.7 million. Baltimore lost 6,738 people. Detroit and Cleveland also saw small declines.

"We are seeing a pattern now that the recession is over, the large-core metro counties are starting to lose population again," said David Egan-Robertson, a demographer with the University of Wisconsin-Madison Applied Population Lab. "And that's true around the country."

In Milwaukee County, 16 of 19 municipalities saw population declines from 2015 to 2016. Oak Creek (+686), Wauwatosa (+346), and Shorewood (+74) all added people.

"The suburbs are starting to pick up in terms of their population gains," said Egan-Robertson.

In Wisconsin, the areas seeing the most rapid population growth are the state's second largest city, Madison, and the surrounding municipalities.

Madison's population grew by 3,938 people from 2015 to 2016. Its total population is now 252,551, up 8.1% since 2010.

Mayor Paul Soglin said those figures are a reflection of the area's economy and quality of life.

"We're building an economy that's designed to create a great place where people want to live and raise their families," he said. "Jobs are at the core, but quality of life is way up there."

Soglin named a few companies that have recently opened offices or expanded in Madison: Zendesk, Exact Sciences, Illumina, and RP's Pasta, which recently merged with two other companies.

He also pointed out the ripple effect from having a business such as Epic, the powerhouse health care software company, in the area.

"You've got a lot of Epic employees who have left the company and are working with other tech companies in the area," Soglin said. "We're trying to develop an enormous reservoir of talented people so that employers know there's a talented workforce here."

The city of Fitchburg, just south of Madison, grew by 3.3% to 28,875 from 2015 to 2016. Since 2010, the city's population has increased by 14.5%.

Fitchburg's mayor, Jason Gonzalez, said a high quality of life, a solid network of school districts and a low unemployment rate are the keys to the city's growth.

"We have high quality, decent paying jobs," he said.

The growth is plainly visible in Fitchburg, Madison and the surrounding areas, Gonzalez said.

"It's almost as if you can't build apartments fast enough at this rate," Gonzalez said.

In Madison, Soglin said, 6,000 new housing units have been built in the downtown area alone.

Verona, right next to Fitchburg and home of Epic, has grown by 21% since 2010. Sun Prairie and Waunakee, which both sit on the northern edges of Madison, have each grown by more than 10% since 2010.

Around the state, the numbers are more mixed. In all, 817 of the roughly 1,850 cities, towns and villages in Wisconsin experienced population losses from 2015 to 2016.

In the Milwaukee area, West Allis (-0.8%), Cudahy (-0.7%), and South Milwaukee (-0.7%) all saw population declines. Sheboygan (-0.3%), Whitewater (-1.1%), La Crosse (-0.3%) and Stevens Point (-0.9%) also lost people.

The city of Waukesha's population declined by five to 72,363 from 2015 to 2016.

The fastest-growing large cities in the country were mostly in the South and West. Phoenix (+32,113), Los Angeles (+27,173) and San Antonio (+24,473) all posted large gains.