Its northern terminus is at the U.S. Route 250 (US 250) and SR 60 concurrency in the village of Savannah.

No portion of SR 545 is included within the National Highway System (NHS), a network of highways identified as being most important for the economy, mobility and defense of the country.

The highway originally consisted of the entirety of the existing SR 288, a portion of SR 97 from SR 288's eastern terminus east a short distance and the entire length of locally-maintained Marion Avenue to the northeast of there into Mansfield.

[3][4] One year later, the highway was extended northeast from Mansfield along the entirety of its present alignment to its current northern terminus at the US 250/SR 60 concurrency in Savannah.

[6] In 1949, the portion of SR 545 between the eastern terminus of SR 288 and Mansfield was removed from the state highway system, in preparation for construction of the Clear Fork Reservoir.