New Jersey Route 166

Route 166 is a short, 3.73-mile (6.00 km) state highway in Ocean County, New Jersey. The route provides an alternate alignment of U.S. Route 9 through South Toms River and Toms River. The southern terminus is at an intersection with U.S. Route 9 northbound in Beachwood, where it heads northward along Atlantic City Boulevard. The route continues until ending where U.S. Route 9 leaves the Parkway north of Toms River. US 9 itself uses the Garden State Parkway to bypass Toms River.

Route 166 is a former alignment of New Jersey Route 4, designated in 1920 and U.S. Route 9, designated in 1927 through Toms River. The highways were realigned when the Garden State Parkway was built, and the original alignment became U.S. Route 9 Alternate in the 1950s, which was eventually replaced with Route 166. The alignment has remained the same since.