New Hampshire Route 175 (NH 175) is a state highway in the U.S. state of New Hampshire. The highway runs north 25.261 miles (40.654 km) from an intersection in Holderness with U.S. Route 3 and New Hampshire Route 25 to an intersection with US 3 in Woodstock. NH 175 is a minor highway that parallels US 3 and Interstate 93 through the valley of the Pemigewasset River. NH 175 has a secondary spur road, , which connects it to downtown Plymouth.