Overview: As the United States spread across the
Appalachians, the Mississippi River became increasingly important as a conduit
for the produce of America’s West (which at that time referred to the land
between the Appalachians and the Mississippi). Since 1762, Spain had owned the
territory of Louisiana, which included 828,000 square miles, and which now
makes up all or part of fifteen separate states between the Mississippi River
and the Rocky Mountains.