New Hampshire Route 140 is a 21.142-mile-long (34.025 km) east–west state highway in central New Hampshire, running from Tilton to Alton.

The eastern terminus is in Alton at NH 11 and New Hampshire Route 28A (Main Street).

In Alton, the road is named the Frank C. Gilman Highway.

NH 140 (along with I-93) is commonly used as an alternative for motorists during the busiest NASCAR events at New Hampshire Motor Speedway in Loudon.

The main highway to the speedway, New Hampshire Route 106, is converted to one-way traffic to accommodate the increased amount of traffic.