The 63.450-mile-long (102.113 km) route traverses an area from US Highway 2 (US 2) near Tioga, in eastern Williams County, to the Canadian border where it continues as Saskatchewan Highway 47 (Hwy 47) in northern Divide County.

[2] ND 40 begins at a junction with US 2 south of Tioga, in eastern Williams County.

[4] ND 40, with ND 5, enters Divide County, and then ND 40 leaves the concurrency with a turn at Noonan, 15 miles (24 km) east of Crosby.

While in Noonan, it crosses an alignment of railroad tracks before continuing north.

The road continues beyond the port of entry and the Noonan-Estevan Highway Border Crossing as Hwy 47 on its way to Estevan, Saskatchewan.