Charting the American Bison Population Decline Over Time

American bison population over time

The American bison is a species of bison that has populated the North American plains for thousands of years. It’s estimated that at one point nearly 30-60 million wandered the Americas. Due to a variety of factors in the 19th century the American bison population rapidly dwindled to the point of near extinction.1

The most widely distributed theory for the disappearance of bison from the plains is due to over hunting by American settlers encroaching into the region. While there is a degree of truth to this, the actual reason is much more complicated.

American settlers certainly had a large role to play in the decline of the bison. Settlers brought their cattle, horses and other animals with them, and fenced off large areas that prevented the nomadic bison from grazing.

Commercial bison hunting also emerged primarily via the John Jacob Astor led American Fur Company. The company operated a series of trading posts along the frontier that purchased over 100,000 bison hides annually. Ironically, Native Americans comprised the majority of bison hide hunters and also sold the valuable tongues and bones.1

From a population between 30-60 million per-Columbus, the American bison population diminished over time to between just 325-1,000 by 1880-1890.1,2

Charting the American Bison Population Decline Over Time

The Devastation of the American Bison Population

The American military also sanctioned the killing of wild bison. At the time the military was engaged in many conflicts with frontier natives. The army knew that the natives relied upon the bison as a primary food source, and thus the removal of their food would make them more dependent on the US government and reduce hostilities.

Bison management and hunting grounds were a key component of the 1868 Treaty of Fort Laramie.

There were two other factors that contributed to the decline of bison populations: disease and lack of land management. These factors go hand in hand. Firstly, before settlers even began to show up in the Great Plains, the native populations there were ravaged by European introduced diseases. The land they had been tending for thousands of years fell into disarray.

American bison hunting over time
Depiction of bison hunting from railroad cars via LOC

Bison will reproduce plentifully if left unchecked and will graze in the same location for months if not hunted and forced to move. The bison began to overwhelm the landscape and ate everything in sight. Within a few generations the bison were critically overpopulated in many areas and many were starving.

In their weakened state they became extremely susceptible to diseases. Cattle introduced some disease, but most were diseases local to their areas. It’s impossible to tell just how many bison were killed from disease vs humans, but there were many factors contributing to their decline.

Luckily, the federal government identified as an endangered species and allowed the species to repopulate. By the 1990’s, bison not privately owned numbered around 25,000, a significant increase from as low as 325 remaining in 1884.


To learn more about US history, check out this timeline of the history of the United States.


1) Lueck, Dean. “The Extermination and Conservation of the American Bison.” The Journal of Legal Studies, vol. 31, no. S2, 2002, pp. S609–52. JSTOR,

2) Flat Creek Inn

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