From 1821 to 1846, the Santa Fe Trail served as an international road for American and Mexican traders. Freight wagons often traveled in parallel columns to minimize dust and to make it easier to circle the wagons at night or in times of danger; although such circles, often more square than round, could provide a defensive position, they were used mostly for convenience, sociability, and as corrals for animals. After the Mexican-American War ended in 1848 and the New Mexico Territory was added to the United States, the trail became a national road for commercial and military freighting, stagecoach travel, emigration, and mail service. Over time, the westward-expanding railroad replaced it, reaching Santa Fe in 1880, and in 1987 Congress designated the route a national historic trail. Although it was primarily a commercial trade route, some women and children traveled with wagon trains, including Marion Sloan Russell, who made five trips across the plains before age fifteen. In 1852, her mother, Eliza St. Clair Sloan Mahoney, left Fort Leavenworth, Kansas, with seven-year-old Marion and nine-year-old Will, heading toward the California gold fields. In return for passage as far as Santa Fe, Eliza agreed to cook for Army officers and a West Point-trained doctor in a wagon train led by wagonmaster Francis Xavier Aubry. The family remained in Santa Fe for four years, and Eliza later made numerous trips between Missouri and Santa Fe, eventually continuing to California, with Marion accompanying her on five of those journeys. In February 1865, Marion married Lieutenant Richard D. Russell at Fort Union, New Mexico, on the Santa Fe Trail, and she died in Trinidad in 1936 at age 92.