Wyoming Highway 343 (WYO 343) is a 5.24-mile-long (8.43 km) north-south Wyoming State Road in northern Sheridan County that connects U.S. Route 14 (US 14) and WYO 345.

Wyoming Highway 343 begins its southern end at U.S. Route 14 at Dayton and from there travels northwest.

[2] At approximately 4 miles into the route, Highway 343 gently curves northeast as it meets Sheridan County Route 118 (Columbus Creek Road).

[3] Shortly thereafter, WYO 343 turns due north.

The entire route is in Sheridan County.