Nearly 1,000 bison have stampeded across South Dakota's prairie land before being corralled into pens during Custer State Park's 47th annual Buffalo Roundup.
Thousands of spectators watched Monday as 60 cowboys and cowgirls on horseback led the creatures over hills and across wide expanses of land.
Park officials created the roundup nearly 50 years ago to manage the park's bison herd. It has since become a multi-day event that draws people from as far away as Germany, Australia and New Zealand.
About 250 of the buffalo will go up for auction on Nov. 17. The buffalo are bought to start or supplement herds, or to be eaten.