In the field, however, NH 10 is cosigned along US 302 for an additional 19.8 miles (31.9 km) from Haverhill to an intersection with New Hampshire Route 18 in Littleton.

NH 10 continues north along the Ashuelot River, through the town of Swanzey and into the city of Keene.

The highway has no major junctions in Lempster and continues north into Goshen where it intersects the northern terminus of NH 31.

The highway continues through Croydon with no major junctions, then into Grantham where it intersects with the northern terminus of NH 114 before interchanging with Interstate 89.

Now running along the eastern bank of the river, NH 10 continues north into the town of Hanover.

After crossing the town line, NH 25 splits off to begin its eastward trek across the state.

It is the shortest state highway in New Hampshire, slightly more than 1⁄2 mile (0.80 km) in length.

The western terminus of NH 10A is on Ledyard Bridge over the Connecticut River, which is the border with Vermont.

Across the bridge, the road becomes Vermont Route 10A (Main Street in the town of Norwich).