Wheat grown in western North Dakota is often transported by rail or truck to ports in the Pacific Northwest where it is typically exported to customers in Asia. Wheat grown in eastern North Dakota often moves by rail or truck to Minneapolis or Duluth. Shipments from Duluth leave the United States through the St. Lawrence Seaway and the Great Lakes during navigation season April 1 - December 25. Wheat leaving Minneapolis is moved by rail or barge down the Mississippi River to ports in the Gulf of Mexico. An increasing amount of wheat is railed directly to Mexico. The Port of Duluth accommodates ocean vessels up to 25,000 tons, while Pacific Northwest and Gulf ports can handle vessels of any size. Ocean freight rates at these ports are very reasonable compared to rates in other wheat exporting countries. U.S. spring wheat and durum can be delivered by rail from the production area to any of the three major ports in about five days or less. There is virtually no degradation of the product during inland transport because the railroads, barge operators and trucking firms are responsible for the product while it is in their control. Since late shipments, grain loss, and quality deterioration result in lost business and profits, U.S. transporters prioritize timely and well-maintained deliveries. . Of the total amount of U.S. hard red spring wheat exported each year, approximately 76% leaves the country via Pacific Northwest ports, 11% from Gulf ports, 5% from the ports in the Great Lakes/St. Lawrence Seaway region and 8% is directly railed to Mexico. In the case of durum, approximately 60% is exported from the Gulf, 36% from the Great Lakes, and 3% through the Pacific Northwest.