The American frontier, also known as the Old West or the Wild West, includes the geography, history, folklore, and culture in 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. 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 tenets and prides of American national identity.
The archetypical Old West period is generally accepted by historians to have occurred between the end of the American Civil War in 1865 until the closing of the Frontier by the Census Bureau in 1890.