NY 315 was assigned as part of the 1930 renumbering of state highways in New York.

Paralleling Big Creek, the route heads northwestward through mostly rural and residential land.

The route, locally known as Buell Avenue along this stretch of its source, crosses several of the creek's tributaries as it progresses towards the hamlet of Deansboro, where it bends slightly westward and uneventfully terminates at NY 12B.

Here, the road makes an S-shaped turn around Big Creek and one finds a rock face with caves and a natural spring.

NY 315 was assigned to its current alignment during the 1930 state highway renumbering.