Third Avenue is a north-south thoroughfare on the East Side of the New York City borough of Manhattan, as well as in the center portion of the Bronx. Its southern end is at Astor Place and St. Mark's Place. It transitions into Cooper Square, and further south, the Bowery, Chatham Square, and Park Row. The Manhattan side ends at East 128th Street. Third Avenue is two-way from Cooper Square to 24th Street, but carries only northbound (uptown) traffic while in Manhattan above 24th Street; in the Bronx, it is again two-way. However, the Third Avenue Bridge carries vehicular traffic in the opposite direction, allowing only southbound vehicular traffic, rendering the avenue essentially non-continuous to motor vehicles between the boroughs.

U.S. Route 1 (US 1) is a part of the U.S. Highway System that extends from Key West, Florida, to the Canada–United States border at Fort Kent, Maine. In the U.S. state of New York, US 1 extends 21.54 miles (34.67 km) from the George Washington Bridge in Manhattan to the Connecticut state line at Port Chester. It closely parallels Interstate 95 (I-95) for much of its course and does not serve as a major trunk road within the state. It is not concurrent with any other highways besides I-95 and (briefly) US 9, and few other state highways intersect it.