Merrimack County, New Hampshire

Merrimack County is a county in the U.S. state of New Hampshire. As of the 2010 census, the population was 146,445, making it the third-most populous county in New Hampshire. Its county seat is Concord, the capital of New Hampshire. The county was founded in 1823 from parts of Hillsborough and Rockingham counties, and is named for the Merrimack River.