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
New France which was granted to Spain, along with the territory to the westthe larger portion of Louisiana. In 1800, Spain returned its portion of Louisiana to France under the secret Treaty of San Ildefonso. However, French leader Napoleon Bonaparte in turn sold it to the United States in the Louisiana Purchase of 1803, permanently ending French colonial efforts on the North American mainland. New France eventually became absorbed within the United States and Canada, with the only vestige remaining under French rule being the tiny islands of Saint Pierre and Miquelon. In the United States, the legacy of New France includes