The following highways are numbered 451:
Canada Ontario Highway 451, commonly called the Queen Elizabeth Way.
Japan Japan National Route 451
Korea, South Jungbu Naeryuk Expressway Branch
United Kingdom from Stourbridge to Great Witley
United States Florida State Road 451 Kentucky Route 451 Louisiana Highway 451 Maryland Route 451 (former) New Mexico State Road 451 Oregon Route 451 Puerto Rico Highway 451 Tennessee State Route 451 Texas Farm to Market Road 451 Wyoming Highway 451