Map of the Oregon Country. Shows boundary on the 54° 40' line near <a href="https://en.wikipedia.org/wiki/Fort_Simpson_(Columbia_Department)" class="extiw" title="w:Fort Simpson (Columbia Department)">Fort Simpson</a>
U.S. Ex. Ex., Charles Wilkes, Esqr., Commander
1841
<a rel="nofollow" class="external autonumber" href="http://memory.loc.gov/cgi-bin/query/r?ammem/gmd:@field(NUMBER+@band(g4240+ct000908))">[1]</a>