U.S. Route 23 Business (US 23 Bus), established in 1960, is a 2.3 miles (3.7 km) business route (co-signed with US 19 Bus) currently starts on Haywood Road then go north on I-26/I-240 (exit 2) back to the main US 23 (exit 3). Historically, US 23 Business continued along Haywood Road, connecting to Clingman Avenue and then to Patton Avenue/US 23. In 1961, it extended over Patton Avenue through downtown Asheville when US 23 moved onto the East-West Freeway. In 1962, it was rerouted to its current alignment from Haywood Road to Hanover Street (now I-26/I-240).
U.S. Route 23 Alternate (US 23A), established in 2006, is an 8-mile (13 km) route follows the old US 23 route through northern Madison County. Starting at the exit 9 interchange from I-26/US 23, it briefly links with US 19 before taking a left turn towards Tennessee. There is no control city for the route as it only connects the communities of California, Faust, and access to the Wolf Laurel gated community and ski resort. The route reunites with I-26/US 23 at the exit 3 interchange. Signage of this alternate route goes by an "A" right of number instead of "ALT" or "Alternate" banner on top (this is the same style used by other alternate routes in Western North Carolina).
BUS US 23 is a 7.42 mile (11.94 km) business route running in Ann Arbor. It was first designated on November 28, 1962 as a business route of US 23. It travels concurrently with both BL I-94 and M-14 over portions of its routing.
In 1962, with the completion of the US 23 freeway in the area, BUS US 23 was designated over the former routing in Ann Arbor. It utilized a portion of the 1958 freeway from the Huron River north to the US 23 freeway. In 1965, M-14 was relocated and the concurrency with BUS US 23 was shortened.
The northern terminus of BUS US 23 is at the western interchange of US 23 and M-14 north of downtown Ann Arbor. The southern terminus is at the interchange with US 23 between Ann Arbor and Ypsilanti. This interchange also includes BL I-94 and M-17.
BUS US 23 is a 4.07 mile (6.55 km) business route running in Rogers City. It was first designated on November 12, 1940 as M-65, and on January 28, 1942 as a business route of US 23.
In 1940, the shoreline routing of US 23 from Rogers City to Cheboygan was opened. Until the designation of BUS US 23 in 1942, the former US 23 was partially designated M-65. Other sections of BUS US 23 were M-91.
The northern terminus of BUS US 23 is at the intersection with US 23 northwest of downtown Rogers City. The southern terminus is at the intersection with US 23 south of Rogers City.
BUS US 23 in Fenton was a business loop serving the city of Fenton, Michigan. It was first designated on September 16, 1958 as a business loop route of US 23. The original routing followed Owen Road and Shiawassee Street into downtown Fenton, before following LeRoy Street (a former routing of US-23) for about four blocks, then following Silver Lake Road back to the US-23 freeway. The loop was rerouted in 1961 with the completion of the US 23 freeway in Genesee and Livingston counties. The southern portion of the loop was separated in 1975 with the creation of a pedestrian mall and the turnback of two blocks of Leroy St. in downtown Fenton. The southern portion of the loop was left as a state trunkline, but unsigned. From that point until around 2004, only the Silver Lake Road portion was signed as Business US-23; guide signage from the US-23 freeway never indicated the presence of the business route, however. The Owen Road/Shiawassee Street portion was eventually signed in 2004, approximately two years before the route was decommissioned. Leroy St. was reopened to auto traffic in 2004, but it was not turned over to the Michigan Department of Transportation to reconnect the existing spur to the unsigned southern portion. The entire trunkline, both signed and unsigned was turned back to local control on December 7, 2006.
In 1929, US 23 was moved to the opposite side of the Saginaw River between Saginaw and Bay City along present-day M-13, with the former route being redesignated US 23A before taking the M-47 designation only a year later. The former US 23A designation is now a part of M-84 between those two cities.
BUS US 23 followed a former routing of US-23 through downtown Saginaw, Michigan. It was co-signed with US-10 (present-day Genesee Street) into downtown Saginaw, then followed M-13 northerly to present-day I-75 exit 153. This business route later became a BL I-75 designation, which was decommissioned in 1971.
Alternate US 23, or ALT US 23, was a 24.8 mile (39.9 km) redesignation of a stretch of US 23 in Michigan from Monitor Township near Kawkawlin to about 4 miles (6.4 km) south of Standish. It was established on 10 6, 1967 In 1967, a stretch of what would later become part of the I-75 freeway was opened between the above 2 mentioned towns, and US 23 was designated on the new road. After the former US 23 was given the ALT US 23 designation, AASHTO, although it has no enforcement authority, did not approve of having two types of US 23's running parallel so close with each other, and after about a year, ALT US 23 became an extension of M-13. The freeway portion from I-75 to Kawkawlin became Connector M-13.