Public Road Miles
Michigan has just over 122,000 miles of highways, roads, and streets, maintained by one of three jurisdictions, either the Michigan Department of Transportation (MDOT), a county road commission or other county agency, or a city or village. Roadway classifications are divided into five "legal systems" for funding through the formulas of the Michigan Transportation Fund including state trunklines, county primary roads, county local roads, city major streets, and city local streets. State trunklines, county primary roads, and city major streets carry most of the vehicle-miles of travel, while county local roads and city local streets are relatively lightly used.
The Washtenaw County Road Commission is the jurisdictional authority over all public roads lying outside the incorporated cities and villages within Washtenaw County, exclusive of any state trunkline highways. At the end of 2010, the Washtenaw County Road Commission certified approximately 590 miles of county primary roads and 1,060 miles of county local roads.
MDOT annually certifies all public roads within the State of Michigan. Certification maps are maintained by the Road Commission and are the basis for determining the amount of money received from the Michigan Transportation Fund. Generally, the Road Commission receives a higher level of reimbursement for primary roads than local roads. Further information on public road miles can be found in the public road mileage charts and the Road Commission maps.