New York State Route 915E (NY 915E) is an unsigned reference route designation for Third Avenue Extension in East Greenbush, located in Rensselaer County, New York, in the United States. The east–west highway extends for 1.67 miles (2.69 km) from an intersection with NY 151 east of the Rensselaer city limits to a junction with U.S. Route 4 (US 4) south of the hamlet of Defreestville. NY 915E was designated as New York State Route 381 from the late 1930s to 1962 and part of NY 43 from that time to the late 1990s, when it gained its current designation.