Deemston is a borough in Washington County, Pennsylvania. It is located about 50 miles away from Pittsburgh, the second largest city in the state.

According to the United States Census Bureau of 2000, Deemston is home to more than 800 residents. The borough has a total area of 9.6 square miles all of it land.

The racial composition of Deemston is more than 99% white with other groups making up less than 1% of the population.

Deemston has more than 300 households. The median income for a household in the borough is $35,598, and the median income for a family is $41,188.