Toward the mid-1800s, the picture of bison on the Great Plains began to change as westward expansion by pioneers, cattle ranching, fashion fads, and development of railroad lines all impacted them. Bison hides were tanned for belts to drive early machinery and made into clothing products, while the tongues were butchered, salted, and sold as a delicacy. In the 1870s, with the economy depressed and jobs scarce, market hunting became a prime way to earn a living, drawing thousands of hunters to the Great Plains because a hunter could earn around $3 per hide, more than factory wages. Hunters focused on hides and tongues, leaving the remaining carcasses to rot on the open prairie, and some westward pioneers slaughtered bison for sport, even shooting them from tracks and railroad cars when trains stopped for large herds. The Sharps rifle made it possible for hunters to harvest over 100 bison per day. During the late 1800s, the United States government encouraged the slaughter of bison to drive the Plains Indians onto reservations by cutting off a source of food, shelter, clothing, and spirit, amid wider conflicts over trespassed hunting lands, broken treaties, and greed tied to markets. After the market hunters came bone collectors, who gathered bison bones into great piles near railroad lines and shipped them east to be ground for fertilizer or used in refining sugar, while bones also supplied products such as buttons, combs, knife handles, and cleansers.