Even though the US government had not given Andrew Jackson permission. But instead of punishing him, government officials decided to take advantage of the situation. After the Seminole War, the United States gave Spain an ultimatum.. police the Florida Territory or cede it to the United States. This was the United States chance to get Florida back from Spain.

In 1819, the United States Secretary of State, John Quincy Adams negotiated a treaty with Spain called the Adams-Onis Treaty. The Adams-Onis Treaty granted the United States the territory of Florida. In addition, it set a boundary between Spain and the United States in the southwest that extended all the way from the Gulf Coast to the Pacific Ocean. In return, the United States promised to recognize Spain's sovereignty over the southwest part of the continent, including the region known as Texas.

With the signing of the Adams-Onis Treaty, the United States stretched from the Atlantic Ocean to the Pacific Ocean. Expansion and settled borders brought Americans new opportunities. Eager for land, farmers moved west in greater numbers. Growth also brought problems. American Indians continued to lose their lands. Tensions between Indian tribes and settlers increased.

The issue of slavery in the western territories divided the nation. Slave owners wanted the right to bring their slaves into the western territories. Those opposed to slavery wanted the territories to be free of slavery. People close to the border between the United States and the Spanish territories struggled with questions of loyalty. All these conflicts would continue to grow in the coming decades.