When they signed the Adams-Onis Treaty, the Spanish gave up their claim to Oregon. *

In 1819, the United States and Spain signed the Adams-Onís Treaty. With this treaty, Spain gave up its lands in the Oregon Country. Spain's territory would end at California's northern border. In 1824, Russia gave up its claims on lands south of Alaska.

Explanation:

your answer would b. the missisipi river

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