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).
People of US-birth and immigrants from Europe began moving westwards, especially after hearing wonderful reports from the Lewis and Clark expedition (1804–06), a US government survey of the new region. In addition, Americans believed in their ‘manifest destiny’, a God-given right and duty to spread out across the land; this philosophy preceded the phrase (first used 1845), and became one of the main justifications for settlement activity in the American West. The Mexican War (1846–48) and subsequent conquest of the southwest, along with the California gold rush (1848), further opened up the country.
The population grew continually and when a particular area reached 60,000, it officially became a state. In 1792, Kentucky became a state, followed by Tennessee in 1796, Ohio in 1803, Indiana in 1816, and Illinois in 1817.
In 1846, Horace Greeley, a New York journalist, wrote an article encouraging young men to go west to find their fortunes, coining the popular phrase, ‘Go west, young man, go west’. Americans of all ages responded, drawn by the promise of free or cheap land, abundant resources, and religious freedom. They headed to Oregon country (the present-day states of Washington, Oregon, Idaho, and parts of Montana and Wyoming) via the Oregon Trail, and California along the California Trail. At this point, no-one settled in the Great Plains because the ground there was covered in sod (soil filled with tough roots), and they did not yet have the tools or the knowledge to cultivate it.
Image: Daniel Boone Escorting Settlers through the Cumberland Gap by George Caleb Bingham, from the Kemper Art Museum.