Luis de Onís, the Spanish minister to the United States, realized that if the United States was unwilling to give back West Florida it would soon take the rest of Florida, too. He was already negotiating with Secretary of State John Quincy Adams over the boundary between the Louisiana Purchase and Spanish Mexico. Perhaps he could get better terms in this discussion by agreeing to give up Florida. Adams, the son of former president John Adams, was intelligent and clever. In the end he got both Florida and what he wanted in the West.
Adams suggested to Onís that if Spain gave up Florida, the United States would then be willing to postpone settling the Louisiana boundary. As Adams well knew, this was exactly the opposite of what Onís wanted. Onís feared that a delay would only increase American demands in the West. Adams was already claiming that the Mexican province of Texas was part of the Louisiana Purchase. He was pressing Onís to accept the Rio Grande as the boundary line between the United States and Spanish Mexico. Therefore, Onís wanted a “safe and permanent” line agreed upon quickly.
Adams eventually suggested a compromise. A western boundary could be drawn that would leave Texas in Spanish hands. He suggested that from a point north of Texas the line should extend west “straight to the Pacific Ocean.” This would give the United States territory all the way across North America.
Onís was unable to get Adams to give up this claim. Finally, he wrote his superiors in Spain. “If His Majesty . . . hasn’t sufficient forces to make war on this country,” he suggested, “then I think it would be best not to delay making the best settlement possible.”
The boundary line that Adams and Onís finally agreed upon followed roughly the present eastern and northern boundary of Texas, then went north to 42° north latitude, then west to the Pacific. Spain kept Texas but abandoned all claims to the Oregon Territory.
When Adams had first suggested extending the boundary line between Mexico and the United States west to the Pacific, Onís had argued that there was no need for such a boundary. He insisted that the entire Pacific Coast belonged to Spain. He denied that the United States had a right to any territory west of the Louisiana Purchase.
Adams, of course, won the argument. However, his success was more a sign of Spain’s weakness than of the strength of his argument. Aside from the explorations of Lewis and Clark, the United States had little on which to base a claim to regions beyond the Rocky Mountains. Nevertheless, Americans were pushing steadily westward, and it was on this basis that Adams staked his claim.
American settlers assumed that the land beyond the Rocky Mountains was eventually to be a part of the United States. Of course, American Indians in the region felt differently, and they fought hard to protect their claims, but that came much later. When Adams and Onís divided the West by drawing a line on a map, the actual invasion by white settlers lay far in the future.
