NY 70 is posted as a north–south highway; however, it is inventoried by
NYSDOT as an east–west route, As such, the route officially begins at an intersection with
NY 436 in the town of
Portage, located in southwestern
Livingston County. It initially heads southward across open fields and past small wooded areas before curving to the east about later. The route continues in this direction for another , intersecting the south end of
CR 7 (Hunt Road) and the north end of
CR 46 (Oakland Street) before crossing into the
town of Nunda. Just east of the town line, NY 70 enters the
hamlet of
Dalton, where the highway connects to the southern terminus of
NY 408 and the northern terminus of
CR 24A (State Street) at a junction north of the community's center. From Dalton southeast to
Canaseraga, NY 70 closely parallels the
Norfolk Southern Railway's
Southern Tier Line as both the road and the rail line run along the base of a valley surrounding
Canaseraga Creek, the source of which is located roughly east of Dalton. The valley takes the route and the railroad southeastward into
Allegany County, where they both pass through the towns of
Grove and
Burns. As NY 70 runs through the two towns, it serves the railside hamlets of
Swain (in Grove) and
Garwoods (in Burns), meeting
CR 24 in the former and
CR 15B in the latter. East of Garwoods, the creek curves to follow a more easterly track, and the valley, NY 70, and the Southern Tier Line all turn eastward to match the change in course. Just over from Garwoods is the creekside village of Canaseraga, a stark departure from the isolated, undeveloped areas that NY 70 serves west of this point. The route intersects
CR 13 and
CR 13A (Church Street) in the center of the village before heading into another stretch of open areas east of the community. About east of Canaseraga, NY 70 intersects
NY 961F, a
reference route signed as a touring route. At this point, the Southern Tier Line heads south to follow NY 961F toward
Hornell and Canaseraga Creek turns north toward the Livingston County village of
Dansville. NY 70, meanwhile, continues generally eastward toward the
Steuben County line, traversing a wide north–south gully that carries
NY 36 from Hornell to Dansville. The eastern track eventually gives way to a northeasterly alignment as the highway crosses into Steuben County and its
town of Dansville. NY 70 ends just into the county at an intersection with NY 36 near the eastern edge of the valley in the hamlet of Dotys Corners. ==History==