By a joint resolution approved June 10, 1910, Congress gave its consent to Oregon and Washington to fix their common boundary in the Columbia River and to cede, the one to the other, islands the title to which had been in dispute. Owing to the continual shifting of the main channel of the Columbia River, it was decided to define the boundary by a series of tangents, the ends of which were recorded geodetic positions. A compact was made by the States of Oregon and Washington, and Congress approved the new boundary on July 31, 1958 (72 Stat. 455). These straight lines connect 191 points between the mouth of the Columbia and the point where the boundary leaves the river and continues eastward along the 46th parallel. These lines approximate the channel of the river, and a point is established on the centerlines of bridges and dams crossing the river. 
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 * 17 April 1824: A Convention of Commerce between the United States and Russia set the northern limit of the Oregon Country at 54 degrees 40 seconds north latitude. (Hayes, 131; Parry 74:135-140) [no northern limit prior]