The failure of these two attempts caused Mr. Astor to turn to the old American Fur Company. The exclusion Act of 1815 enabled him to buy at his own price the North-west Fur Company's posts on the upper rivers, and the American Company rapidly extended its trade over all the country, from Lake Superior to the Rocky Mountains. Its posts multiplied in every direction, and at an early date steamboats began to do its business up the Missouri River from St. Louis. It gradually absorbed lesser concerns, such as the Missouri Fur Company, and the Columbia Fur Company, and in 1823 was reorganized under the name of The North American Fur Company. In 1834, Astor sold his interests to Chouteau, Valle and Company, of St. Louis, and retired from the business. At this time the general western limit of the territory operated in by this formidable company was the northern and eastern slope of the mountains which bound the Yellowstone Park on the north and east. Its line of operations was down the river to St. Louis, and its great trading posts were located at frequent intervals between. The third of the great rival companies was the Rocky Mountain Fur Company, which originated in St. Louis in 1822, and received its full organization in 1826 under the direction of Jedediah Smith, David Jackson and William Sublette. Among the leading spirits, who at one time or another guided its affairs, was the famous mountaineer James Bridger to whom frequent reference will be made. This company had its general center of operations on the head waters of Green River to the west of South Pass. Unlike the other companies, it had no navigable stream along which it could establish posts and conduct its operations. By the necessities of its exclusively mountain trade it developed a new feature of the fur business. The _voyageur_, with his canoe and oar, gave way to the mountaineer, with his saddle and rifle. The trading post was replaced by the annual rendezvous, which was in many points the forerunner of the later cattle "roundups" of the plains. These rendezvous were agreed upon each year at localities best suited for the convenience of the trade. Hither in the spring came from the east convoys of supplies for the season's use. Hither repaired also the various parties of hunters and trappers and such bands of Indians as roamed in the vicinity. These meetings were great occasions, both in the transaction of business and in the round of festivities that always prevailed. After the traffic of the occasion was over, and the plans for the ensuing year were agreed upon, the convoys returned to the States and the trappers to their retreats in the mountains. The field of operations of this company was very extensive and included about all of the West not controlled by the Hudson's Bay and American Fur Companies.