Before 1800, the North American Great Plains were home to one of the most extraordinary wildlife spectacles on Earth. Historians estimate that the bison population reached between 30 and 60 million, with herds so massive that they could darken the sky for hours as they moved across the landscape. By the late 19th century, however, this vast population had nearly vanished. By 1889, only 1,091 bison remained worldwide, mostly in private herds. The dramatic decline was largely the result of a deliberate policy by American authorities aimed at weakening Indigenous nations by depriving them of their primary food source. This was accompanied by widespread hunting to facilitate the expansion of European settlers into the region. William Hornaday, a naturalist and later a key figure in conservation, documented the destruction of the bison herds and called the federal government's role inexcusable. His 1889 census revealed that only 85 bison remained truly wild in the United States, with the rest confined to private ranches. While the government's actions nearly led to the species' extinction, it was private ranchers who ultimately played a critical role in saving the bison. Between 1880 and 1900, ranchers collected the last surviving bison and began crossbreeding them with domestic cattle. This was done to create more manageable animals, easier to contain and less prone to disease. The crossbreeding, however, left a lasting genetic impact. For decades, the Yellowstone bison herd was considered genetically pure, but that belief was challenged in 2022. A study led by researchers at Texas A&M University compared the genomes of modern bison with historical samples and nearly 1,800 cattle. The findings revealed that all North American bison, including those from Yellowstone, carry small traces of bovine DNA. Even the Yellowstone herd, once seen as a genetic exception, showed a minimal but measurable amount of cattle DNA—0.24% in one individual. This discovery upended previous assumptions about the genetic purity of the species. Despite the genetic legacy of crossbreeding, the situation has sparked new possibilities. With the understanding that no bison are completely free of bovine DNA, some conservationists are reevaluating strict crossbreeding restrictions. This shift could lead to more flexible management strategies aimed at preserving the species' genetic diversity. While the story of the bison is one of near-extinction and human intervention, it also reflects a complex but hopeful path forward in conservation.