Wikipedia:Featured topics/U.S. Highways in Michigan
The US Highways in Michigan are the segments of the national United States Numbered Highway System that are owned and maintained by the US state of Michigan, totaling about 2,300 miles (3,701 km). The longest of these is US Highway 23 (US 23) at around 362 miles (583 km). On a national level, the standards and numbering for the system are handled by the American Association of State Highway and Transportation Officials (AASHTO), while the highways in Michigan are maintained by the Michigan Department of Transportation (MDOT). The original highways were approved on November 11, 1926, by AASHTO including 14 mainline highways. A handful of these original highway designations no longer run within Michigan, and a few numbers have been added since the 1930s. Since 1999, there have been 13 mainline highways, and with the creation of a business route for Constantine, there are a total of 30 special routes in the state. Several highways have been converted to freeways, some of which are now Interstate Highways and no longer part of the U.S. Highway System. These freeway conversions started in the 1940s and 1950s and continued through to the turn of the 21st century.