SR 637 begins at an intersection with U.S. Route 224 (US 224) in rural Van Wert County.

The route heads north as a two-lane highway passing through farmland, with a few houses.

The road enters Grover Hill, passing through residential properties and has an intersection with SR 114.

The highway leaves Grover Hill and passes through farmland in rural Paulding County.

ODOT's 2009 annual average daily traffic (AADT) calculations showed that the lowest traffic levels were present on the section that is between Paulding County Road 60 (Matson Road) and SR 613, where only 870 vehicles used the highway daily; the peak traffic volumes were 2,630 vehicles AADT along a section of SR 637 that is concurrent with SR 111.