C-73 (Michigan county highway)

County-Designated Highway System
Highway markers for A-2 in Allegan County and H-58 in Alger County
Zone boundary highways highlighted in red
System information
Maintained by various county road commissions
Length:	1,241.614 mi (1,998.184 km)
Formed:	October 1970 (1970-10)
Highway names
County-Designated:	A-nn through H-nn
County Road:	County Road nn (CR nn, Co. Rd. nn)
System links
County-Designated Highways

The County-Designated Highways in Michigan comprise a 1,241.6-mile-long (1,998.2 km) system of primary county roads across the US state of Michigan. Unlike the State Trunkline Highway System, these highways have alphanumeric designations with letters that correspond to one of six lettered zones in the state. The CDH system was created in 1970 in response to the business concerns of a woman from Saugatuck. Her one-woman crusade in the 1960s started after the highway in front of her motel was turned over to local control as a county road and removed from state highway maps when the nearby freeway opened. After nearly a decade of efforts, the first two test highways were designated, one each in the Lower and Upper peninsulas of the state and included on the 1970 state highway map. The CDH system was created and expanded in scope c. October 5, 1970, after it was approved by the County Road Association of Michigan and the State Highway Commission.

The system uses eight lettered zones which are divided by major state highways. Each county road in the system is designated with the zone letter followed by a number. Six of the zones, A–F, are in the Lower Peninsula while the Upper Peninsula is divided into the remaining two, G and H. There have been a total of 66 different highways designated in seven of the zones; as of 2015 no E highways have been named. Participation by the county road commissions is optional, and not all counties use the system. One additional highway, H-16, has appeared on state maps since the 1980s although it is not a part of the system. Of the highways designated, two were removed from the system and later partially restored.

When the Interstate 196 (I-196) freeway was built in the Saugatuck area in the 1960s, US Highway 31 (US 31) was shifted to the new freeway. The former route along Blue Star Highway was returned to county jurisdiction, which removed the various state highway markings from the roadway and displaced Blue Star Highway from the state highway maps of the time. At the time, Mr. and Mrs. Howard and "Gene" Temple owned a motel along the roadway in Saugatuck, and they were dismayed over the number of canceled reservations they were receiving because guests could not find their business. Mrs. Temple approached the Village of Saugatuck and the local chamber of commerce to get better highway markings for the area. She even contacted state legislators and members of the State Highway Commission. No changes were made, even though businesses along Blue Star Highway were suffering from a lack of traffic.