N.D. Cent. Code § 24-01-33
The highway authorities of the state, or any county, or municipality may designate and establish controlled-access highways as new and additional facilities or may designate and establish an existing street or highway as included within a controlled-access facility. The state or any of its subdivisions has authority to provide for the elimination of intersections at grade of controlled-access facilities with existing state and county roads, and municipal streets, by grade separation or service road, or by closing off such roads and streets at the right-of-way boundary lines of such controlled-access facility; and after the establishment of any controlled-access facility, no highway or street which is not part of said facility may intersect the same at grade. No municipal, county, or state highway, or other public way may be opened into or connected with any such controlled-access facility without the consent and previous approval of the highway authority in the state, county, or municipality having jurisdiction over such controlled-access facility. Such consent and approval may be given only if the public interest is served thereby.
N.D.C.C. § 24-01-33