In US history, the period of settlement 1800–50 when Americans pushed the frontier westwards in search of land and resources, economic opportunities, a better life, and, for some, religious freedom. In 1803 the USA comprised 17 eastern and central states, however the Louisiana Purchase (land bought from France in 1803) expanded its territory by 2,144,000 sq km/828,000 sq mi (the present-day states of Louisiana, Missouri, Arkansas, Iowa, Nebraska, North Dakota, South Dakota, and Oklahoma).