At the time, the Lousiana Purchase doubled the size of the United States giving her power and resources(land, water, trade routes, minerals). It also gave America access to the ports in the area greatly aiding trade. The land had belonged to France before it was sold to America, so the purchase removed their presence in the area for the most part. It also fixed ties with France who had previously asked for aid in the French Revolution to which America said no; giving France money in the form of this purchase healed the connection slightly.
The Oregon territory officially belonged to Britain, but was mostly inhabited by Native Americans. It was a very large area that caused many disputes between the European colonists due to the fur-trade. America gained the land (segments of present-day Idaho, Oregon, Washington, Wyoming, and Montana) in 1859 when Oregon officially became a state. Many Native Americans were also sent here as America continued to gain territory. The giving over of the land was used to settle the boundary dispute between America and Britain.
The US expanded their territory and the purchase secured American control of the Mississippi river which literally doubled the size of the nation. Although they had bought the land from the French, the natives still lived on the land and wouldn't let go easily thus this resulted in a number of wars such as the battle of new Orleans between the government and the natives.