One mile south of the border, the highway crosses the Pembina River and enters Neche.

Just south of the county line is the small city of Hoople, which ND 18 passes just east of.

The route travels about halfway between the larger cities of Grafton and Park River.

Fourteen miles south of the southern end of the ND 17 concurrency, ND 18 enters Grand Forks County.

About three miles into Grand Forks County, the route passes east of Inkster.

Fourteen miles south of Inkster, ND 18 intersects with US 2, a major east–west route of the northern United States.

Fourteen miles south of Arthur, the route turns east and enters Casselton.

The concurrency ends two miles east of Lidgerwood and ND 18 continues to head south.