In 1846, the british and united states made what decision regarding oregon?

They created the 49nth parallel in the Treaty of Oregon due to a rising population in the area. It created a permanent border between the U. S and British Canada.

In 1846, the British and the United States decided to renegotiate their initial agreement, due mainly to the increasing population in the area. They signed the Oregon Treaty, which permanently established the 49th parallel as the boundary between the United States and British North America to the Pacific Ocean.