Ohio State Route 4 is a north-south highway across Montgomery County. This provides a vital surface highway through the county and Metro-Dayton. OH St Rt 4 passes through the following towns in Montgomery County. Germantown West Carrollton Dayton Riverside OH St Rt 4 is multi-plexed in Montgomery County. Ohio State Route 725, at Germantown. Ohio State Route 48, at Dayton. Interstate 70, at Huber Heights.