Josiah Gregg's activities as a physician were incidental to his other interests. Gregg did a multitude of things and did most of them well. Driven by an inner restlessness, at one time or another he was a surveyor, schoolteacher, law student, trader, storekeeper, guide and interpreter, cartographer, botanist, ornithologist, war correspondent, and physician.
He is best known for his vivid and precise descriptions of Western America in the early 1800s. His only book, Commerce on the Prairies, may have done as much as any publication to entice the populace westward. An accounting of his four trips by wagon train to Santa Fe, it set a tone and showed an eye for detail that was unsurpassed in its description of the rolling plains, the daily chores of the wagon train, Indian life, and the nuances and invigoration of traveling on the frontier. First published in 1844, early copies of the book
Kyner JL. Doctor Josiah GreggScientist of the Southwest, Portrayer of the Santa Fe Trail. JAMA. 1973;224(1):101–105. doi:10.1001/jama.1973.03220140069014