- Southern Terminus:
- Columbus Avenue and Westchester Avenue (CR 62) in West Harrison
- Northern Terminus:
- Lake Street (CR 32) and Harrison Boulevard (CR 32B) in West Harrison
- 0.77 miles
Underhill Avenue is a short road connecting the downtown area of West Harrison near Silver Lake to the Cross Westchester Expressway (I-287). It begins at Columbus Avenue just north of Westchester Avenue (CR 62), the service road of the expressway, and runs north for about three quarters of a mile to an uncontrolled intersection with Harrison Boulevard (CR 32B) where it turns into Lake Street (CR 32). The entire length is a two-lane undivided road.
There is no exit from the Cross Westchester Expressway (I-287) for Underhill Avenue. Motorists wishing to access it must use exit 8 from the westbound side, follow the signs toward White Plains Avenue (NY 127), and then turn at the uncontrolled intersection with Columbus Avenue where there is no signage. Motorists travelling east can use exit 8E and then turn around by following the signs toward Anderson Hill Road (CR 18) and then Westchester Avenue (CR 62) west.