This route is part of a multi two-state route 15 that begins at Florida and ends at Georgia at the North Carolina state line.

From there, SR 15 travels north on Narcoossee Road, west on Hoffner Road, north on Conway Road through Conway, west on Lake Underhill Road, and west on South Street (northbound) and Anderson Street (southbound) on both sides of SR 408 to downtown Orlando.

It then travels north on Mills Avenue and follows US 17 all the way to downtown Jacksonville.

SR 15 is practically unsigned, except in three places: The rest is signed as various U.S.

The alternate route in Seminole County was going to be a bypass of Sanford, but construction of SR 400 (Interstate 4) relegated it to a minor road, and it became CR 15 in the 1980s.