State Trunk Highway 51
Route information
Maintained by WisDOT
Existed	1918–1926
Location
Country	United States
State	Wisconsin
Highway system
Wisconsin State Trunk Highway System Interstate US State Scenic Rustic
← US 51 → WIS 52

State Trunk Highway 51 (often called Highway 51, STH-51 or WIS 51) was a number assigned to two different state highways in the U.S. state of Wisconsin:

• Highway 51 from 1917 to 1923, along the current route of U.S. Highway 63 from Turtle Lake to Spooner.
• Highway 51 from 1923 to 1936, currently routed as Highway 72 from Ellsworth to Downsville.
• For the highway in Wisconsin numbered 51 since 1926, see U.S. Highway 51.