Rock County's population grew by 809 people in 2018, according to estimates released by the U.S. Census Bureau.
The county's total population was estimated at 163,129. The population growth in 2018 was slightly less than the 926 people added in 2017, according to population estimates.
Wisconsin's total population growth estimate as of July 1, 2018 was 5,813,568, up 2.2 percent from 5,687,282 reported in 2010. Population estimates for the state indicate 22.1 percent of the population is under the age of 18 and 16.5 percent are over the age of 65.
Milwaukee County is the most populous county in Wisconsin with 2018 population estimate at 948,201, up slightly from 947,736 in 2010.
Dane County is the second most populous county in the state at 542,364 people, according to the U.S. Census population estimate, up from 488,067 in 2010.
Rock County is the ninth most populous county out of Wisconsin's 72 counties.
Walworth County, which is the state's 14th most populous county, had an estimated population of 103,718 in 2018, up from 102,228 in 2010.
Green County had a population estimate of 36,929 in 2018, up slightly from 36,842 in 2010.
Jefferson County had a population estimate of 85,129 in 2018, up from 83,683 in 2010.