U.S. Route 4 (US 4) is a part of the United States Numbered Highway System that runs from East Greenbush, New York, to Portsmouth, New Hampshire. In the U.S. state of New York, US 4 extends 79.67 miles (128.22 km) from an intersection with US 9 and US 20 in East Greenbush to the Vermont state line northeast of Whitehall. While the remainder of US 4 east of New York is an east–west route, US 4 in New York is signed north–south due to the alignment the route takes through the state. The portion of the route between Waterford and Whitehall is part of the Lakes to Locks Passage, an All-American Road.

East Greenbush is a town in Rensselaer County, New York, United States. It is a suburb of Albany. The population was 16,748 at the 2020 census. The word Greenbush is derived from the Dutch het groen bosch, referring to the pine woods that originally covered the land. The first settlement of the land now known as East Greenbush was made by tenants under patroon Kiliaen van Rensselaer circa 1630. The town was established in 1855 as Clinton, and was renamed in 1858. It is mostly suburban along its major highways and rural in the southwestern and northeastern corners.