Susan Shelby was born to a wealthy family on their plantation near Danville, Kentucky. Her paternal grandfather was Isaac Shelby, a hero of the American Revolutionary War and the first governor of Kentucky. In 1845, at age 18, she married Samuel Magoffin, a trader on the Sante Fe Trail 27 years her senior. The following year, she accompanied him on a wagon train trading journey out of Independence, Missouri, becoming one of the first American women to make the trip. With war just beginning between the USA and Mexico, it was a particularly dangerous time to travel this region. They traveled to Santa Fe, New Mexico, then headed south to El Paso del Norte, Chihuahua, and Saltillo. Her health suffered from the hardships of the journey and she gave birth to a baby son who died. In 1848, the couple returned to Kentucky, where they had a daughter in 1851. In 1852, they moved to Barrett's Station, near Kirkwood, Missouri, where Susan's husband bought a large estate. Susan had a second daughter in 1855 and died soon after, at age 28. She kept a diary of her travels from 1846 to 1847, in which she recorded her experiences and her impressions of the Mexican and native American people she encountered. It was published in 1926 as Down the Santa Fe Trail and into Mexico: the diary of Susan Shelby Magoffin, and serves as a valuable historical resource.