The United States
Thirteen years after the end of the French and Indian War, the American colonies declared independence, and in 1783 Britain ceded its empire south of the Great Lakes and east of the Mississippi River to the United States. Twenty years later, France sold the Louisiana Territory from the Mississippi River westward to the United States, giving the new nation control of the entire continent. The Mississippi River was now at the center of the country. But the River itself remained in contention until Britain ceded control to the United States after the War of 1812.
In 1796, George Washington appointed Andrew Ellicott to survey the border with Spanish Florida. Ellicott worked together with Spanish commissioners, and, in 1803, he published his journal, which included maps of the Mississippi River.
In 1820 and 1832 Henry Schoolcraft conducted two expeditions to find the source of the Mississippi River. Schoolcraft concluded that the Mississippi River begins at Lake Itasca, in northern Minnesota.
Even after the advent of the steamboat, and several decades of surveying and development, parts of the Mississippi River Valley remained pristine. In 1854, Canadian adventurer Laurence Oliphant traveled the upper Mississippi and described the Minnesota territory as largely wilderness, noting that the Indians cultivated wild rice in the River’s tributaries.2
2. Oliphant, 212.