• Pre-1700s — 25 to 30 million bison roam the nation’s plains.

• 1700 — The horse reaches the Great Plains.

• 1720 — Comanches establish hunting territories in southern Plains.

• 1804-06 — The Lewis and Clark expedition travels the upper Missouri River.

• 1820 — Bison are extinct east of the Mississippi River.

• 1820s — The market for robes made of buffalo skins kicks in. Trading continues on the Northern Plains until 1880.

• 1860s-80s — The railroad divides bison into northern and southern herds.

• 1871 — A hide market develops as railroads penetrate Kansas, tanning technologies evolve and hunting continues all year.

• 1872 — Sharp’s .50 caliber rifle is developed.

• 1874 — Comanche defeat opens bison range for hide hunting.

• 1874-80 — Bison are decimated in Texas and Oklahoma.

• 1870s-80s — Cattle increase on the Great Plains.

• 1871-75 — About 4 million bison are killed in the southern herd; 1.4 million hides are shipped from Dodge City, Kan.

• 1880-83 — The northern herd is reduced to less than 100 animals not including 200 in Yellowstone National Park.

• 1889-1901 — The Yellowstone herd falls to 25 animals.

• 1889 — William Hornaday’s survey finds 1,091 bison in North America.

• Late 1800s — Private captive herds are established.

• 1899 — Bison herd established at the Bronx Zoo.

• 1902 — Bison restoration begins in Yellowstone National Park.

• 1907 — Bronx Zoo ships 15 bison by railroad to the new Wichita Reserve Bison Refuge in Cache, Okla.

•1911 — Bison declared no longer in danger of extinction.

•1915 — American Bison Society feels it has achieved its goal of preserving bison through the establishment of four federally sponsored bison preserves.

• 1934-35 — Sioux and Crow establish herds in South Dakota and Montana.

• 2002 — More than 232,000 bison exist in private herds in the U.S.; 150,000 are being raised in Canada.

From www.americanbisonsociety online.org. The American Bison Society originally was founded in 1905 by pioneering conservationists Theodore Roosevelt and William Hornaday. In 2005, the society was re-launched by the Wildlife Conservation Society to secure the ecological future of bison in North America.