The 9,655-mile state trunkline system in Michigan is laid-out, designed, and marked by the Michigan Department of Transportation (MDOT), which is also responsibile for the system's maintenance, either directly or through contracting with local units of government. Michigan is regarded as being the second state in the U.S. to set up a numbered and posted state trunkline system. While Wisconsin is given the credit for creating the first such system in 1917, Michigan's was organized within a year after that. Even before that point, however, in 1913 the Michigan State Legislature passed the "State Trunk Line Act," which authorized the designation of a state highway network totalling almost 3,000 miles of roadway. The act stipulated the State Highway Department would design, build and maintain highway bridges 30 feet in length or longer, if the county or local government improved three miles of adjacent road.
As of 2010, there are 122,901 miles of roads in Michigan, with responsibility for these roads divided by the state (9,655 miles), counties (90,208 miles), cities and villages (21,247 miles), and some in the federal jurisdiction (1,791 miles). According to MDOT, Michigan ranks 48th in the U.S. in percentage of roads under the jurisdiction of the state as compared to all roads system in the state (7.9%). Also, 84% of Michigan's population currently resides within two miles of a road on the state highway system.
As for the highway route designations itself, Michigan generally does not have any special "practices," such as clustering of route numbers, with the exception of what could be termed a "minimalist" strategy. This is shown when a freeway or expressway is opened along a new alignment and the former route is generally turned back to local control. However, the mileage of the state trunkline system has, itself, remained relatively constant over the last several decades, with only 500 miles separating the minimum and maximum during that time peroid. The table below illustrates this:
*Totals do not include federally-owned mileage, such as forest roads and roads in federal installations.
MDOT does correctly note that "the density of development varies considerably throughout Michigan, with the heaviest concentration existing in the southeast portion of the lower peninsula." Even with this obvious disparity in settlement density, there has always been a level of "geographic equity" in the organization of the state highway system. MDOT notes their aim has been to "provide everyone with reasonable access to a state highway, regardless of where they live." Over the nearly 100-year history of the signed state highway system, MDOT and its predecessors have done a excellent job of adhearhing to their goal. With the changes coming to Michigan's state highway system, the Department of Transportation is committed to maintaining this balance. However, they state "the definition of 'reasonable access' may change, more or less proportionately, for everyone in Michigan."
For more in-depth information about the Michigan state trunkline system, please feel free to explore the many pages on this site using the drop-down menus at the top of each page or select from any of the items below:
- Michigan's Route Systems - information about the various types of signed highway route systems.
- Michigan's Route Markers - all about the diamond state trunkline marker in use since 1918, as well as the many other types of route markers used on and off the trunkline system ever since.
- Master List: 1918-Present - the comprehensive listing of every route designation ever used in Michigan.
- Highway Listings - every highway is listed here with facts. details and history about each.
- Historical Overview - historical highlights about the Michigan state trunkline system.
- The History of Roads in Michigan - a special section relating the history of roads from prehistoric Indian Trails to modern times.
- In Depth: News & Articles - in-depth stories, histories and information.