Spain agreed to give up both east and west Florida in exchange for America's forgiving of a Spanish debt of $5 million. Spain also agreed to surrender all claims to land east of the Mississippi River, and the U.S. did the same for what is now Texas, leaving that territory under Spanish control.

In addition, Adams got America's Western boundary drawn to the Pacific Ocean, from the Gulf of Mexico to the Rocky Mountains and along the 42nd parallel (the northern border of California) -- an extraordinary diplomatic accomplishment. Adams was also responsible for defining the U.S.-Canadian border as part of the Treaty of 1818 with England.