Wikipedia:Naming conventions (U.S. state and territory highways)

This Naming Convention is intended to standardize the naming formats used in articles pertaining to highways in the United States.

The highway types covered by this convention have two naming formats – official name and article title – which can be the same. The official name is the naming format typically used by the state department of transportation (DOT) or the general public, and is what should be used to refer the highway in article prose. The article title is a disambiguated form obviously used for article naming, and should only be used in article prose if a sentence would otherwise be ambiguous.

If you disagree with the conventions described here, or wish to add to them, please discuss it on the |talk page. These conventions were established through previous debates, and any proposals to change such conventions may be contentious (see also the Arbitration Committee Highways case).

U.S. state highways
The following are systems of state highways maintained and numbered by each U.S. state, territory or district. The naming conventions listed below may be supplemented by guidelines of individual state highway task forces under the U.S. Roads WikiProject (please see WP:USRD/SUB for a list). The standardized abbreviations in use in the jct template are also listed below for convenience.

The official name is to be used when writing about the road in an article; only use the article title in another article if the sentence would otherwise be ambiguous. Never use a colloquial title other than those listed above, unless you are adding a mention of its existence to the article.

Official nicknames for highways (i.e. Golden State Freeway, Tri-State Tollway, New Jersey Turnpike) may be used if the DOT uses it. However, colloquial names such as The Loneliest Road in America should not be used.

Interstate and U.S. Routes
The following are systems of national highways maintained by the states which have their numbering assignments made by the American Association of State Highway and Transportation Officials (AASHTO).