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
Mississippi River from Napoleon of France, Spain ceded an undefined portion of West Florida to France. When France then sold the Louisiana Territory to the U.S. in 1803, a dispute arose again between Spain and the U.S. on which parts of West Florida exactly had Spain ceded to France, which would in turn decide which parts of West Florida were now U.S. property versus Spanish property. These aspirations ended when Spain was pressured into signing Pinckney's Treaty in 1795. France reacquired 'Louisiana' from Spain in the secret Treaty of San Ildefonso in 1800. The United States then secured effective control of the