Colonial history of the United States Lower Louisiana. This vast tract was first settled at Mobile and Biloxi around 1700, and continued to grow when 7,000 French immigrants founded New Orleans in 1718. Settlement proceeded very slowly; New Orleans became an important port as the gateway to the Mississippi River, but there was little other economic development because the city lacked a prosperous hinterland. In 1763, Louisiana was ceded to Spain around New Orleans and west of the Mississippi River. In the 1780s, the western border of the newly independent United States stretched to the Mississippi River. The United States reached an agreement with Spain for
French people in Nebraska as present-day Illinois. Trappers and traders established relationships with Native American tribes at major points around the Great Lakes and along the Mississippi and Missouri rivers. In the Treaty of Fontainebleau in 1762, France ceded its lands west of the Mississippi River to Spain. In 1794 a French trapper named Jean-Baptiste Truteau established a trading post 30 miles up the Niobrara River. The next year, in 1795, Jacques D'Eglise traveled the Missouri River Valley on behalf of the Spanish crown. Searching for the elusive Northwest Passage, D'Eglise did not go any further than central North Dakota. In 1803 the United