Wikipedia:WikiProject U.S. Roads/Ohio/Historical information from the 1920s

Most of the information here is from [1] and [2].

The system of routes that exists today first appears on the 1923 ODOT map. The 1926 map is the first with city insets, and shows preliminary U.S. Routes but also the old State Route numbers. The 1927 map shows the effects of the renumbering.

State Route 1, IN to Wheeling
- Now U.S. Route 40
State Route 2, IN to PA
- Now U.S. Route 6, State Route 2, State Route 51, U.S. Route 20
State Route 3, Cincinnati to Cleveland
- Now State Route 3, State Route 226, State Route 3, U.S. Route 42
State Route 6, Cincinnati to MI
- Now State Route 4, State Route 73, Dixie Highway (old U.S. Route 25), State Route 25, U.S. Route 24
State Route 7, IN to Conneaut
- Now U.S. Route 50, State Route 264, Harrison Avenue, U.S. Route 52, State Route 41, Roush Hill Road, U.S. Route 52, State Route 7, St. Clair Avenue, Spruceville Road, State Route 7, State Route 164, South Avenue, State Route 7
State Route 9, Cincinnati to MI
- Now U.S. Route 127, State Route 249, State Route 15
State Route 25, Cincinnati to Friendship
- Now State Route 125
State Route 26, Dunlap to Griffith
- Now Kemper Road, State Route 4, Glendale Milford Road, Plainfield Road?, Cooper Road, State Route 126, U.S. Route 50, State Route 550, State Route 26
State Route 27, Cincinnati to Enterprise
- Now U.S. Route 50, State Route 28, U.S. Route 50, State Route 159, State Route 180
State Route 28, Cincinnati to West Jefferson
- Now U.S. Route 42, State Route 142
State Route 74, Cincinnati to south of Seaman
- Now State Route 32
State Route 124, Sharon to Franklin
- Now Cincinnati Dayton Road, Dixie Highway (old U.S. Route 25)
State Route 125, Le Sourdsville to Lebanon
- Now State Route 63
State Route 126, Hamilton to IN
- Now State Route 177, State Route 130, U.S. Route 27
State Route 127, IN to Hamilton
- Now State Route 129
State Route 128, Cleves to Hamilton
- Now State Route 128
State Route 129, Cincinnati to IN
- Now U.S. Route 27, State Route 126
State Route 130, IN to Bridgetown
- Now Harrison Avenue (old U.S. Route 52)
State Route 131, Milford to Fayetteville
- Now State Route 131
State Route 132, New Richmond to Williamsburg
- Now State Route 132, State Route 276
State Route 223, northeast of Ross to McGonigle
- Now U.S. Route 27
State Route 224, northwest of Hamilton to IN
- Now State Route 177