Good grass and shelter drew ranching interests to the badlands, and after the bison were killed a Texas trail drive brought 4,000 longhorn cattle into this region in the fall of 1884. Other trail drives followed, bringing thousands more. Longhorns, hardy animals, handled the long walk from Texas well, adapted quickly on the open range, and were ready for market in two years. Twenty years later they had almost disappeared from the Northern Plains as overgrazing and severe winters damaged the open range cattle industry. By the early 1900s, ranchers were replacing longhorns with newer, more productive breeds, though a few people acted to save the longhorn from extinction. Today a small herd of 10-25 longhorn steers in the North Unit, obtained from Fort Niobrara National Wildlife Refuge in Nebraska, remains as a reminder of the bygone open range cattle era.