How Ocean Ships Reach Duluth, Minnesota—1,500 Miles Inland

How Ocean Ships Reach Duluth, Minnesota—1,500 Miles Inland

Duluth, Minnesota—at the western tip of Lake Superior—is the world's most inland major seaport accessible to ocean-going vessels. The secret: the Great Lakes–St. Lawrence Seaway System.

The Waterway Chain

1. Atlantic Ocean → Gulf of St. Lawrence
2. St. Lawrence River (with locks at Montreal, Beauharnois, etc.)
3. Lake Ontario
4. Welland Canal (bypasses Niagara Falls; 8 locks lift 99 m / 325 ft)
5. Lake Erie
6. Detroit River → Lake St. Clair → St. Clair River
7. Lake Huron
8. St. Marys River / Soo Locks (Sault Ste. Marie; lifts 7 m / 21 ft)
9. Lake Superior → Duluth–Superior Harbor

Key Stats

• Total distance: ~3,700 km (2,300 mi) from Atlantic to Duluth.
• Locks: 16 total (13 Canadian, 3 US).
• Max vessel size ("Seawaymax"): 225.5 m (740 ft) long, 23.8 m (78 ft) beam, 8.08 m (26.5 ft) draft.
• Season: Late March to late December (ice-free).
• Cargo: Iron ore (taconite), grain, coal, steel, wind turbine components.

Economic Impact

The port handles ~35 million metric tons annually, supporting 11,500 jobs and $1.5B in business revenue. It's a critical node in the North American industrial heartland—turning a Great Lakes port into a global gateway.