N.D. Cent. Code § 24-01-10
The governing board of any county, municipality, or township, as the case may be, may enter into a written agreement with the director for the construction of a roadway or structure of greater width or capacity than would be necessary to accommodate the normal state highway traffic, upon any state highway within its boundaries, and may appropriate from any funds available, and pay into the state highway fund, such sum or sums of money as may be agreed upon. Nothing herein contained prevents any such municipality from constructing the portions of the street not included in the state highway system independent of any contract with the department, if such construction conforms to such reasonable regulations as the department may prescribe as to grade and drainage.
N.D.C.C. § 24-01-10