Wikipedia:Naming conventions (numbered highways)

Principles
Each highway falls into an individual and specific numbering system, (usually) assigned by a governmental body. For instance, the United States Numbered Highways are assigned by the American Association of State Highway and Transportation Officials, the numbered Routes in New Jersey are assigned by the New Jersey Department of Transportation, and the Great Britain road numbering scheme is assigned by the Department for Transport (for major roads). Each system shall be considered on its own when deciding naming conventions.

This agency typically has a certain way of referring to the highway - for instance State Road 50 in the U.S. state of Florida. Often this is unclear; a common naming convention for the system should be agreed upon, by weighing both what the agency uses and what the public uses. Every highway in the system shall use the same naming convention (unless it is a redirect to a highway in a different system - either a higher system, like State Route 80 (California) to Interstate 80, or the local name of the road, like State Road 300 (Florida) to St. George Island Bridge).

The Florida state highway should be disambiguated by putting said region first. Thus:
 * State Road 50 (Florida), not
 * Florida State Road 50.

This is because Wikipedia has an international audience.

Note the capitalization that is used in lists and categories too.

Sometimes a disambiguation is not needed; for instance the Interstate Highway System is the only system to use the "Interstate X" convention.