From U.S. Wheat Associates
The Columbia Snake River System is the network of federal dams and locks on the Columbia River and connected water bodies, including the Snake River. This system enables grain barges to carry wheat 360 miles from Lewiston, Idaho, to export elevators as far west as Longview, Wash.
In marketing years 2019/20 and 2020/21, more than 55% of all U.S. wheat exports* moved through the system by barge or rail. Of the more than 15.0 million metric tons (MMT) of U.S. wheat exported from Pacific Northwest (PNW) export elevators each of those years, an estimated 4.6 MMT arrived by barge.
In addition, an estimated 10% of total annual U.S. wheat exports each year passes through the four locks and dams on the Snake River between Lewiston, the most inland port in the nation, and its confluence with the Columbia River. For more facts, read the rest of the article here.