The median income of Washington County residents was an inflation-adjusted $29,590 per year. Washington County had 83,897 households in 2017, with a population of 207,661.
The county with the highest median resident income in the state was Chester County. Chester County's median income was $40,145 per year after adjusting for inflation – $10,555 more than Washington County. It had 188,613 households in 2017 and a population of 514,652.
Forest County had the lowest annual resident income among counties in Pennsylvania, with a median income of only $15,451 per year. That was $14,139 less than the median income in Washington County at the time. Forest County had 1,473 households in 2017 and a population of 7,388.
The table below shows the state's counties ranked by median annual resident earnings in 2017.