Clarksville is an unincorporated community in Howard County; the second wealthiest county in the United States according to the U.S. Census Bureau. According to the U.S. Census Bureau, Clarksville District 5 has a population of 56,239, with an estimated average income of $195,124, with median income of $160,606.
In 1699, Thomas Browne, a Patuxent Ranger, ranged the river from the Snowden plantation to where Clarksville is sited. The area was settled with tobacco plantations such as Folly Quarter and Hobbs Regulation with slave labor. In 1838, Dr. William Watkins of Richland Manor proposed the "Howard District" of Anne Arundel County, which became Howard County in 1851. Clarksville's name originates from John R. Clark's family who immigrated from Ireland to the Howard District of Anne Arundel County in 1790. The land he purchased included Jack Howard's blacksmith shop, one of the few African American operated blacksmith's in the county. Clarksville postal office listed the population as just 65 in the 1930s with the key industry of agriculture and limestone mining. Numerous apple orchards were situated between Clarksville and Ashton. In 1869 the town became the terminus of the ten mile Ellicott City and Clarksville turnpike built over the old Sandy Spring road, a ten-mile private toll road created in a time before county maintained roads which later became route 108.