M-123 (Michigan highway)

M-123
Route information
Maintained by MDOT
Length	96.071 mi[1] (154.611 km)
Existed	1936[2]–present
Tourist routes	Lake Superior Circle Tour Tahquamenon Scenic Heritage Route
Major junctions
South end	I-75 near St. Ignace
Major intersections	H-40 in Trout Lake M-28 near Eckerman H-37 near Newberry
North end	M-28 near Newberry
Location
Country	United States
State	Michigan
Counties	Mackinac, Chippewa, Luce
Highway system
Michigan State Trunkline Highway System Interstate US State Byways
← M-122 → M-124

M-123 is a state trunkline highway in the eastern Upper Peninsula of the US state of Michigan. It is one of only a few highways in Michigan that curve around and form a U-shape. In fact, M-123 has three intersections with only two state trunklines; it meets M-28 twice as a result of its U-shaped routing. M-123 also has a rare signed concurrency with a County-Designated Highway in Michigan; in Trout Lake, there is a concurrency with H-40. All of M-123 north of M-28 is a Scenic Heritage Route within the Michigan Heritage Route system.

The highway was first designated before 1936 along a section of its current routing. Sections added since then encompass segments formerly belonging to US Highway 2 (US 2) and M-48. The last changes came to the highway in 1962 and 1963, when the northern end was extended and the southern end was truncated slightly.