Pittsburg is a town in Coos County, New Hampshire, United States. The population was 867 at the 2000 census. It is the northernmost town in New Hampshire and the largest town by area in the state, more than twice the size of the next largest town, Lincoln. U.S. Route 3 is the only major highway in the town, although the northern terminus of New Hampshire Route 145 also lies within Pittsburg. Pittsburg is part of the Berlin, NH–VT Micropolitan Statistical Area.