National Geographic : 1941 Jun
00 ©Brubaker Aerial Surveys Had Its Waters Been Muddy, Early Explorers Might Not Have Missed the Columbia's 3-Mile Mouth Many million tons of shipping a year pass between the two jetties; yet the much-sought river was long a mystery(pages 790, 791). Sand Island, on the Washing ton side, and Clatsop Spit, Oregon (right), have shifted about, but there is now a 35-foot dredged channel to Portland, 113miles inland. Beyond thejetty (right) lies Astoria, and facing it the sand bar where horse-seining is carried on (Plates IX, X, and XI). In the distance, Mount St.Helens and Mount Adams arealmost inline.