thumb|Mercersburg Academy Chapel
Mercersburg is a borough in Franklin County, Pennsylvania, United States. The borough is southwest of Harrisburg, the state capital. As of the 2020 census, Mercersburg had a population of 1,507.
Due to its location in a rural area, it had a relatively large percentage of African-American workers who had been enslaved from the Revolution. It was called "Black Town" in the early 19th century before incorporation under its current name. Refugee African Americans escaping from slavery in the South also settled here, and the area was known as "Little Africa".
Mercersburg was platted in 1780. The borough was named after Hugh Mercer, a general and hero in the American Revolutionary War. A post office has been in operation at Mercersburg since 1812.
Located near the southern border of Pennsylvania, the rural community became a place of refuge during the antebellum years for escaped African Americans who had been enslaved in the South. Some came to the area via the Underground Railroad. After the American Revolution, Pennsylvania had abolished slavery. In this area were communities of free African Americans who had worked in agriculture. It was relatively easy for refugees to join their communities after passing over the border of Maryland.
In later years, black folks moved away from here as they were at risk from slavecatchers, especially after passage of the Fugitive Slave Act in 1850, which had more stringent rules against free states. Many African Americans moved to Philadelphia, which had a large and free black community, which helped new arrivals get settled. Philadelphia also provided more job opportunities.
In 2010, 6.49% of the population was of African American descent, out of a total of 1,561 persons.
The Mercersburg Historic District, Lane House, and Mercersburg Academy are listed on the National Register of Historic Places.
Geography
Mercersburg is located in southwestern Franklin County and has a total area of , all land.
As of the census