The following highways are numbered 503:
Canada Alberta Highway 503 Manitoba Provincial Road 503 Newfoundland and Labrador Route 503 Ontario Highway 503 (former)
Costa Rica National Route 503
India National Highway 503 (India)
Japan Japan National Route 503
Malaysia Malaysia Federal Route 503
United States County Road 503 (Brevard County, Florida) Maryland Route 503 (former) County Route 503 (New Jersey) Ohio State Route 503 Washington State Route 503 Territories Puerto Rico Highway 503