The fur trade became a booming business in the wilderness west of St. Louis, with trapping centered mainly on the upper Missouri River in the Dakotas and Montana and furs sent downriver to St. Louis for sale. In 1809, William Clark and Manuel Lisa helped create the Missouri Fur Co., one of Missouri’s first fur trading companies, with headquarters in St. Louis. The company was eventually absorbed by John Jacob Astor’s American Fur Co. of New York, whose western division in St. Louis was operated by Pierre Chouteau Jr. and Bernard Pratt; they later bought their share and established Pierre Chouteau Jr. and Co. The American Fur Co. pioneered the use of steamboats on the Missouri River, transforming a trade that had previously depended on small keelboats. The most famous fur trade steamboat was the Yellowstone, built in Kentucky for the Missouri’s dangerous waters. On its maiden voyage from St. Louis beginning April 16, 1831, it reached Fort Tecumseh on June 9, six hundred miles farther up the Missouri River than any earlier steamboat had gone, then returned to St. Louis on July 15 loaded with furs. Its success opened the way for the expansion of regular trade. As the demand for men on steamboats grew, St. Louis’s Missouri Gazette and Public Advertiser printed a February 13, 1822 notice seeking one hundred men to ascend the Missouri River to its source for one, two, or three years under Major Andrew Henry.