The median income of St. Mary's County residents was an inflation-adjusted $40,735 per year. St. Mary's County had 39,276 households in 2017, with a population of 110,979.
The county with the highest median resident income in the state was Howard County. Howard County's median income was $53,458 per year after adjusting for inflation – $12,723 more than St. Mary's County. It had 111,337 households in 2017 and a population of 312,495.
Somerset County had the lowest annual resident income among counties in Maryland, with a median income of only $19,650 per year. That was $21,085 less than the median income in St. Mary's County at the time. Somerset County had 8,362 households in 2017 and a population of 25,801.
The table below shows the state's counties ranked by median annual resident earnings in 2017.