List of highways numbered 503
The following highways are numbered 503:
Canada
- Alberta Highway 503
- Manitoba [Provincial Road 503]
- Newfoundland and Labrador [Route 503]
- Ontario Highway 503
Costa Rica
- National Route 503
India
- National Highway 503 (India)
Japan
- Japan [National Route 503]
United States
- County Road 503 (Brevard County, Florida)
- Maryland Route 503
- County Route 503 (New Jersey)
- Ohio [State Route 503]
- Washington State Route 503