Did the Rocky Mountains Form the Northern Boundary of Oregon Country? No.

The northern boundary of Oregon Country was the 49th parallel north (established by the 1818 Anglo-American Convention and confirmed by the 1846 Oregon Treaty). This line runs from the Rocky Mountains' eastern flank westward to the Pacific—not along the Rockies themselves.

Geographic Clarification

• The Rockies run north-south; the 49th parallel runs east-west.
• The boundary begins at the Rockies' continental divide (Lake of the Woods to the Rockies was settled earlier) but follows the parallel, not the range.
• North of the 49th parallel: British/Canadian territory (New Caledonia, Columbia District). South: U.S. claim.

Oregon Country Defined

Original region: West of Continental Divide, north of 42° (Spanish/Mexican border), south of 54°40′ (Russian claim), west to Pacific. The 1846 treaty split it at 49°.

The Rockies were the eastern boundary of Oregon Country, not the northern.