The American frontier, also known as the Old West, popularly known as the Wild West, encompasses the geography, history, folklore, and culture associated with the forward wave of American expansion in mainland North America that began with European colonial settlements in the early 17th century and ended with the admission of the last few western territories as states in 1912 (except Alaska, which was not admitted into the Union until 1959). This era of massive migration and settlement was particularly encouraged by President Thomas Jefferson following the Louisiana Purchase, giving rise to the expansionist attitude known as "Manifest Destiny" and the historians' "Frontier Thesis". The legends, historical events and folklore of the American frontier have embedded themselves into United States culture so much so that the Old West, and the Western genre of media specifically, has become one of the defining periods of American national identity. The archetypical Old West period is often cited by historians to have occurred between the end of the American Civil War in 1865 and the 1890 U.S. census. Others, including the Library of Congress and University of Oxford, often cite differing points reaching into the early 1900s; typically within the first two decades. A period known as "The Western Civil War of Incorporation" lasted from the 1850s to 1919. This period included historical events synonymous with the archetypical Old West or "Wild West" such as violent conflict arising from encroaching civilization into frontier land, the removal and assimilation of natives, consolidation of property to large corporations and government, vigilantism, and the attempted enforcement of laws upon outlaws. In 1890, the Census Bureau released a bulletin stating: "Up to and including 1880 the country had a frontier of settlement, but at present the unsettled area has been so broken into by isolated bodies of settlement that there can hardly be said to be a frontier line. In the discussion of its extent, its westward movement, etc., it can not, therefore, any longer have a place in the census reports." Despite this, the later 1900 U.S. census continued to show the westward frontier line. By the 1910 U.S. census though, the frontier had shrunk into divided areas without a singular westward line of settlement. An influx of agricultural homesteaders in the first two decades of the 20th century, taking up more acreage than homestead grants in the entirety of the 19th century, is cited to have