The counties that contain Chicago and Detroit and the city of Baltimore were the biggest population losers in the United States from 2015 to 2016, according to a Census Bureau report.

Cook County, Ill., where Chicago is the county seat, had the largest population loss of any county in the country from 2015 and 2016. Between July 1, 2015 and July 1, 2016, Cook County lost a net of 21,324 people to hit 5,203,499, according to the Census Bureau.

Wayne County, where Detroit is the county seat, had the second largest population loss of any county in the nation; and Baltimore, Md., an independent city that the Census Bureau counts as a county, had the third largest population loss.

Wayne County lost a net of 7,696 people during the year, ending up with a population of 1,749,366. Births outnumbered deaths in the county 23,209 to 18,231, and 4,279 people moved into the county from foreign countries. But at the same time, 17,346 people moved out of Wayne County to other places in the United States.

In Baltimore, the population dropped 6,738 to 614,664.

For population gains, Maricopa County, Ariz., where Phoenix is the county seat, had the largest population gain of any county in the country.

“Maricopa County, Ariz., replaced Harris County, Texas, as the county with the nation's highest annual population growth, according to U.S. Census Bureau population estimates released today,” said a release by the bureau. “Harris County was the largest numeric gainer for eight years in a row.”

From July 1, 2015 to July 1, 2016, Maricopa County’s population climbed by a net of 81,360 to 4,242,997.

Harris County, Texas, where Houston is the county seat; and Clark County, Nev., where Las Vegas is the county seat; ranked second and third for largest population growth from 2015 to 2016.

Harris County saw a net increase of 56,587 people to a total population of 4,589,928—this was even though the county saw a net of 16,225 residents move to other parts of the United States.

When measured by which was the “fastest growing” by percentage of population increase as opposed to “largest-gaining” in actual population numbers, The Villages metropolitan area in Florida led the nation with 4.3 percent population growth from July 1, 2015 to July 1, 2016. The Villages, according to the Census Bureau is an area to the west of Orlando.

The second fastest-growing metropolitan area in the country during the year was the Myrtle Beach-Conway-North Myrtle Beach area of South Carolina and North Carolina. It grew by 3.9 percent. The third fastest-growing metropolitan area—at 3.6 percent—was the Bend-Redmond area of Oregon.