U.S. Route 1 Business is a four-lane surface road that provides an alternate route to the Trenton Freeway (US 1) northeast of Trenton in Mercer County, New Jersey. The route is 2.73 miles (4.39 km) long and runs between US 1 in Trenton and Lawrence Township. On the border of Trenton and Lawrence Township, US 1 Bus. intersects the northbound direction of US 206 at the Brunswick Circle. The route was once part of a longer U.S. Route 1 Alternate, which continued southwest through downtown Trenton and into Morrisville, Pennsylvania.

U.S. Route 1 (US 1) is a U.S. Route which parallels the East Coast of the United States, running from Key West, Florida, in the south to Fort Kent, Maine, at the Canadian border in the north. Of the entire length of the route, 66.06 miles (106.31 km) of it runs through New Jersey. It enters the state from Pennsylvania on the Trenton–Morrisville Toll Bridge over the Delaware River in the state capital of Trenton, running through the city on the Trenton Freeway. From here, US 1 continues northeast as a surface divided highway through suburban areas, heading into Middlesex County and passing through New Brunswick and Edison. US 1 merges with US 9 in Woodbridge, and the two routes continue through northern New Jersey as US 1/9 to the George Washington Bridge over the Hudson River in Fort Lee. At this point, the road continues into New York City along with I-95.