Josiah Gregg (1806-1850) was a merchant, explorer, naturalist, and author of the American Southwest and Northern Mexico. He had training in both law and medicine, and practiced both with distinction. He is most famous for his book Commerce of the Prairies, which came out in two volumes in 1844. It was an account of his time spent as a trader on the Santa Fe Trail before the Mexican-American War. The Book established Gregg's literary reputation, and he was hired as a news correspondent during the Mexican War. After the war, he participated in the California Gold Rush.

Gregg's book Commerce of the Prairies, published in two volumes in 1844, was an account of his time spent as a trader on the Santa Fe Trail from 1831 to 1840 and includes commentary on the geography, botany, geology, and culture of New Mexico. Gregg wrote about local people and described Indian culture and artifacts. Volume 2 of 2.