There are 24 counties in Maryland. In 2019, the most populous county in Maryland is Montgomery County, adjacent to Washington, D.C. and one of America's most affluent counties, with a population of 1,058,810. This represents population growth of 8.47% since the 2010 census. Other populous counties in Maryland include Prince George's County (912,756), Baltimore County (832,468), Baltimore city (611,648), Anne Arundel County (573,235). These are the only Maryland counties with a population of more than 500,000. All five counties have experienced positive population growth since the last census except Baltimore city, which has a population that has declined by 1.51%.
The least populated county in Maryland is Kent County with 19,384 residents. Since the last census, Kent County's population has grown by -4.07%. Following Kent County, the least populated counties in Maryland include Somerset County (25,918), Garrett County (29,233), Dorchester County (32,162), Caroline County (33,193), and Talbot County (37,103). These are the only counties below 40,000 residents. All six counties have experienced negative population growth except Caroline County, which has grown very modestly by 0.41%.
Howard County has experienced the highest population growth in Maryland since the last census with a growth rate of 11.26% to a total 2019 population of 321,113. Other counties that have posted population growth of more than 5% since the 2010 census include Charles County (8.53%), Montgomery County (8.47%), Frederick County (7.62%), and St. Mary's County (6.53%). The county that has experienced the most significant decline is Allegany County with -4.48% growth since the census.