In 2019, St. Mary's County, MD had a population of 112k people with a median age of 36.7 and a median household income of $89,845. Between 2018 and 2019 the population of St. Mary's County, MD grew from 111,531 to 112,290, a 0.681% increase and its median household income declined from $90,438 to $89,845, a −0.656% decrease.
The 5 largest ethnic groups in St. Mary's County, MD are White (Non-Hispanic) (74.1%), Black or African American (Non-Hispanic) (14.5%), White (Hispanic) (3.94%), Two+ (Non-Hispanic) (3.38%), and Asian (Non-Hispanic) (2.55%). 0% of the households in St. Mary's County, MD speak a non-English language at home as their primary language.
97.7% of the residents in St. Mary's County, MD are U.S. citizens.
In 2019, the median property value in St. Mary's County, MD was $301,300, and the homeownership rate was 71%. Most people in St. Mary's County, MD drove alone to work, and the average commute time was 30.4 minutes. The average car ownership in St. Mary's County, MD was 2 cars per household.