U.S. Federal Route 1 is a north-south highway in Southeastern New Hampshire. It runs completly within Rockingham County. This enters New Hampshire, from Massachusetts, near Seabrook. From here it runs north along the Interstate 95/New Hampshire Turnpike corridor to the Maine State Line, at Portsmouth. U.S. Rt. 1 passes through the following towns in Rockingham County. Smithton Seabrook Hampton Falls Hampton North Hampton Portsmouth U.S. Rt. 1 is not multi-plexed in Rockingham County. U.S. Rt. 1 intersects the following highways in Rockingham County. New Hampshire State Route 107, at Seabrook. New Hampshire State Route 84, at Seabrook.