National Bison Day: The National Mammal That Came Back From 1,091

The American bison is the largest land mammal in North America, and since 2016 it has been the national mammal of the United States. Before the 1800s, somewhere between 30 and 60 million of them grazed the continent. By 1889, a count for the Smithsonian found 1,091 left alive. National Bison Day, on the first Saturday of November, marks the animal that came back from that number.

The Senate Sets the Date Every Year

National Bison Day is a Senate resolution, passed fresh each year, and the day has been marked since 2012. The 2026 resolution, S. Res. 945, was submitted by Senator John Hoeven with 18 cosponsors and names Saturday, November 7th, as National Bison Day. The year before, S. Res. 475 named November 1, 2025. Both use the same rule: the first Saturday of November.

The national mammal designation came separately. The National Bison Legacy Act adopted "the mammal commonly known as the 'North American bison'" as the national mammal of the United States, and it became law on May 9, 2016. Its findings record that 2014 was the third annual National Bison Day.

Because the day floats, it lands on November 7th in 2026 and November 6th in 2027. World Numbat Day, set by the same first-Saturday rule, falls on the same day both years.

Tens of Millions, Then 1,091

The National Park Service puts the bison population before the 1800s at 30 to 60 million, and the Smithsonian's National Zoo gives estimates as high as 100 million. What followed, between about 1820 and 1880, the Park Service calls the Great Slaughter: railways, rifles and an international trade in buffalo hides, alongside military policy that targeted the herds as a way to control American Indians. In 1873 the Secretary of the Interior wrote that "the civilization of the Indian is impossible while buffalo remain on the plains."

William Hornaday tallied what was left in a report for the Smithsonian. The report, dated May 1, 1889, concluded that the whole number of bison alive was 1,091. Only 85 of them were wild and unprotected in the United States.

Even Yellowstone was not safe. Poachers cut the park's herd to about two dozen animals by 1902.

How the Herds Came Back

On December 8, 1905, Hornaday, Theodore Roosevelt and others formed the American Bison Society to save the species. Two years later, on October 11, 1907, the society sent 15 captive-bred bison from the New York Zoological Park, now the Bronx Zoo, to the Wichita Mountains, the first wildlife refuge in the United States. The National Bison Legacy Act calls it the first successful reintroduction of a mammal on the brink of extinction back into its natural habitat. A small group of ranchers did their part too, gathering the remnants of the scattered herds in the late 1800s.

Today, by the Park Service's count, about 31,000 bison, roughly 11% of the total, are managed for conservation, and around 360,000 are raised as livestock. The Department of the Interior supports about 20 herds across a dozen states, roughly 11,000 animals on some 4.6 million acres. The 2026 Senate resolution counts almost 25,000 bison on more than a million acres of Tribal land in 22 states.

Yellowstone is the only place in the United States where bison have lived continuously since prehistoric times, and its herd, once down to two dozen, has ranged from 3,500 to nearly 6,000 in recent years. The species is still listed as Near Threatened on the IUCN Red List. The 2016 assessment gives the reason: wild bison depend on ongoing conservation work, and only a handful of populations are large enough to be considered viable.

The Animal Itself

A bull bison weighs up to 2,000 pounds, and a cow up to 1,000. A mature bull stands 5.5 to 6.5 feet tall at the hump. For all that bulk, a bison can run at about 30 to 35 miles per hour. Most live 12 to 15 years, and a few reach 20. They roll in the dirt, a habit called wallowing, to shed biting flies and tufts of molted fur.

The name has a small argument attached. Bison is the correct scientific and common name, but buffalo is widely used and accepted. True buffalo are Old World animals, such as the Cape buffalo and the water buffalo.

Seeing One Safely

Yellowstone's rule is to keep at least 25 yards, about 23 meters, from bison at all times, and never to approach one for a photo. They look calm, but bison have injured more people in Yellowstone than any other animal.

A Herd Rebuilt From a Thousand

The bison went from tens of millions to a count that fit in one table, and came back because a few people refused to let that table be the last word. National Bison Day is a good day to remember how close that was.

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