The following highways are numbered 251:
Canada Manitoba Provincial Road 251 Prince Edward Island Route 251 Quebec Route 251
Costa Rica National Route 251
Japan Japan National Route 251
Korea, South Honam Expressway Branch
United Kingdom road B251 road
United States Alabama State Route 251 California State Route 251 Florida State Road 251 (former) Georgia State Route 251 Illinois Route 251 K-251 (Kansas highway) Kentucky Route 251 Minnesota State Highway 251 Montana Secondary Highway 251 New York State Route 251 Ohio State Route 251 Oklahoma State Highway 251A Oregon Route 251 Pennsylvania Route 251 South Dakota Highway 251 Tennessee State Route 251 Texas State Highway 251 Farm to Market Road 251 (Texas) Utah State Route 251 (former) Virginia State Route 251 Washington State Route 251 (former) West Virginia Route 251 Wyoming Highway 251 Territories: Puerto Rico Highway 251