State Route 172 (SR 172) is an east–west state highway in the northeastern portion of the U.S. state of Ohio. Its western terminus is at its interchange with U.S. Route 30 (US 30) about one mile (1.6 km) west of East Greenville near Dalton, and its eastern terminus is at US 30 about two miles (3.2 km) west of Lisbon. The route stays near US 30 for its entire route, and some of the current Route 172 actually served as previous alignments of US 30. The Lincoln Highway ran along portions of what is now SR 172 where US 30 also runs or used to run, from its west end to East Canton.