New Hampshire Route 123 (abbreviated
NH 123) is a secondary north–south
state highway in southwestern
New Hampshire. The southern terminus of the route is at the
Massachusetts state line in
Mason where, as Mason Road, the road continues as an unnumbered local road in the town of
Townsend. The northern terminus, as signed, is at the
Vermont border, where NH 123 continues west for a half-mile to
U.S. Route 5 as Vermont Route 123. Route logs, however, place the terminus at
New Hampshire Route 12 in
Walpole.