The route begins at an intersection with NY 38 in the town of Newark Valley just south of the line for the eponymous village.

NY 38B was established in 1948 as a spur from Newark Valley to Union Center, but only the section in Broome County was maintained by the New York State Department of Public Works.

As early as 1961, Tioga County officials lobbied the state to take over their section but was denied on account of lower Annual Average Daily Traffic (AADT) counts.

Just east of that, the road crosses Crocker Creek, then the Broome County line and enters the town of Maine.

Passing a junction with County Route 86 (CR 86; Old Newark Valley Road), NY 38B continues into the hamlet of Union Center.

When the Broome County section came under state control, they rebuilt the roadway through that area only, leaving the Tioga side as decrepit.

[9] In November, the Governor of New York Nelson Rockefeller announced that bids would open on December 14 for the reconstruction project, costing $2.985 million (1967 USD).

The project would also have special 12 feet (3.7 m) climbing lanes for hills, a new bridge over Crocker Creek, and improvements to six intersections along the road.