How did Spain play a role in Americans moving west?

Spain played a significant role in American westward expansion by establishing early colonial settlements and claims in the Southwest, including areas that would become Texas, California, and New Mexico. Their exploration and mapping of these regions laid the groundwork for later American settlers and traders. Additionally, Spain's eventual relinquishment of these territories through treaties, such as the Adams-Onís Treaty of 1819, facilitated American migration and the pursuit of Manifest Destiny. The cultural and economic exchanges that occurred during this period also influenced the development of the American frontier.