Minnesota constitution
Article XIV
Section 7

There is hereby created a county state-aid highway fund. The county state-aid highway fund shall be apportioned among the counties as provided by law. The funds apportioned shall be used by the counties as provided by law for aid in the construction, improvement and maintenance of county state-aid highways. The legislature may authorize the counties by law to use a part of the funds apportioned to them to aid in the construction, improvement and maintenance of other county highways, township roads, municipal streets and any other public highways, including but not limited to trunk highways and municipal state-aid streets within the respective counties.