After World War II, the Soviet Union and the United States were the two most powerful countries left in the world. The Cold War was a period of tension between the two countries over ways of life. The two countries tried to get other countries on their side.
In 1846, the United States and Great Britain signed the Oregon Treaty. In this treaty, Oregon Country was split with the U.S. gaining sole possession of the territory south of the 49th parallel, and Great Britain gaining sole possession of the land to the north.10.In 1853, the United States sent diplomat James Gadsden to Mexico to renegotiate the border between the U.S. and Mexico.. From 1818 to 1846, the United States and Great Britain administered the territory in Oregon together. This was a compromise until both countries could agree on how to divide the land between them.
In 1846, the border between U.S. and British territory was formally established at the 49th parallel â the part of the territory that was given to Britain would ultimately become part of Canada. Oregon was officially admitted to the union as a state on February 14th, 1859.