American Old West: Missouri trader William Becknell arrives in Santa Fe, New Mexico, over a route that became known as the Santa Fe Trail.

The American frontier, also known as the Old West, and 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 contiguous 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 historians' "Frontier Thesis". The legends, historical events and folklore of the American frontier, known as the frontier myth, 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 features of American national identity.

Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it borders Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas to the south and Oklahoma, Kansas, and Nebraska to the west. In the south are the Ozarks, a forested highland, providing timber, minerals, and recreation. At 1.5 billion years old, the St. Francois Mountains are among the oldest in the world. The Missouri River, after which the state is named, flows through the center and into the Mississippi River, which makes up the eastern border. With over six million residents, it is the 19th-most populous state of the country. The largest urban areas are St. Louis, Kansas City, Springfield, and Columbia. The capital is Jefferson City.

William Becknell was an American soldier, politician, and freight operator who is credited by Americans with opening the Santa Fe Trail in 1821. He found a trail for part of the route that was wide enough for wagon trains and draft teams, making it easier for trader and emigrants along this route. The Santa Fe Trail became an early major transportation route through central North America that connected Franklin, Missouri with Santa Fe, New Mexico, serving both trading and emigrant parties. It served as a vital commercial highway from the 1820s until 1880, when the railroad was introduced to Santa Fe. Becknell made use of long-established trails made by Native Americans, and Spanish and French colonial explorers and traders for centuries before his trip.