Puerto Rico Highway 21

Puerto Rico Highway 21 (PR-21) is the main highway to get to the Medical Center and Veterans Hospital in San Juan, Puerto Rico. It begins at PR-19 in Guaynabo to San Juan before ending at PR-1.

History
PR-6 was previously numbered as PR-21. Perhaps there were plans to connect current PR-21 to current PR-6, but such plans were never realized.