Use these forms, as appropriate in the context, for highways identified by number. For example,
- U.S. Highway 1
- U.S. Route 1
- U.S. 1
- state Route 34
- Route 34
- Interstate Highway 495
- Interstate 495
On second reference only for “Interstate,” I-495.
When a letter is appended to a number, capitalize it but do not use a hyphen. For example,
- Route 1A
See also AP Style Addresses and AP Style Numbers.