Answer:
They wanted to settle boundary issues from the Mississippi River to the Pacific Ocean.
Explanation:
By the early 1800s, Spain began to lose control of its New World colonies, especially the most treasured Mexico. During this period, Florida had become a difficulty to Spain as they could not manage to set fortification and send settlers. Spain resolved to give up the territory to the United States in negotiation for settling the boundary conflict. The boundary established in 1819 by the Adams Onis Treaty (the Florida Purchase Treaty) between the United States and Spain. The border set in the region of the western side of the Mississippi River. The border was again reaffirmed in 1828 through the Treaty of Limits after Mexico got its independence from Spain.