The Carns State Aid Bridge crosses the Niobrara River about 10.8 miles northeast of Bassett, between Rock and Keya Paha counties. Completed in 1913 as six 54-foot spans, it is the oldest remaining structure built under Nebraska's state-aid bridge program, and it was listed on the National Register of Historic Places in 1992. After a span washed out in 1962, two salvaged steel trusses were added.

The March 2019 flood damaged the south approach. The Nebraska Department of Transportation began building an 850-foot concrete replacement bridge in March 2025, with completion expected in mid-2026. For floaters on the Niobrara National Scenic River, Carns is about the halfway point between the U.S. 183 (former Highway 7) landing and the Highway 137 landing. There is no public river access here.