Clarksville is a town in northern Coös County, New Hampshire, United States.

It was purchased by Benjamin Clark of Boston and Joseph Murdock of Norwich, Vermont.

In the late 19th century, major industries included starch and maple sugar.

New Hampshire Route 145 traverses the western end of the township, running south from Pittsburg village into Stewartstown.

Prior to the construction of U.S. Route 3 along the Connecticut River, this was the only road north to Pittsburg.

[1] The highest point in Clarksville is Crystal Mountain, at 3,230 feet (980 m) above sea level, near the town's southern border.

About 5.4% of families and 3.7% of the population were below the poverty line, including none of those under the age of eighteen and 8.7% of those sixty-five or over.