The Santa Fe Trail was a 19th-century transportation route through central North America that connected Franklin, Missouri with Santa Fe, New Mexico. Pioneered in 1821 by William Becknell, it served as a vital commercial and military highway until the introduction of the railroad to Santa Fe in 1880. At first an international trade route between the United States and Mexico, it was the 1846 U.S. invasion route of New Mexico during the Mexican–American War.
After the U.S. acquisition of the Southwest, the trail helped open the region to U.S. economic development and settlement, playing a vital role in the expansion of the U.S. into the lands it had acquired. The road route is commemorated today by the National Park Service as the Santa Fe National Historic Trail. A highway route that roughly follows the trail's path through the entire length of Kansas, the southeast corner of Colorado and northern New Mexico has been designated as the Santa Fe Trail National Scenic Byway.