The 1837 Great Plains smallpox epidemic spanned 1836 through 1840, reaching its height after the spring of 1837, when an American Fur Company steamboat, the SS St. Peter, carried infected people and supplies up the Missouri River in the Midwestern United States.
[1] The disease spread rapidly to indigenous populations with no natural immunity, causing widespread illness and death across the Great Plains, especially in the Upper Missouri River watershed.
[5] First afflicted Native Americans after it was carried to the Western Hemisphere by early European explorers, with credible accounts of epidemics dating back to at least 1515.
The Assiniboine First Nation had controlled much of this territory, but were forced to give it up as their population decreased dramatically as a result of the disease's high mortality rate.
As its use became widespread in Europe, deployment of the smallpox vaccine in North America was praised by Thomas Jefferson as a means of preserving lives.
In the United States, the Mandan tribe had previously experienced a major smallpox epidemic in 1780–1781, which severely reduced their numbers to less than a few thousand.
The Great Plains smallpox epidemic of 1837 spanned thousands of miles, reaching California, the Pacific Northwest coast, and central Alaska before finally subsiding in 1840.
[15] On August 11, Francis Chardon, a trader at Fort Clark, wrote, "I Keep no a/c of the dead, as they die so fast it is impossible," and by the end of the month, "the Mandan are all cut off except twenty-three young and old men.
"[16] Once the disease reached Fort Union, there was an effort to prevent its spread, but transmission was already underway, and it would eventually decimate the Assiniboine.
[18] Halsey wrote, "I sent our interpreter to meet them on every occasion, who represented our situation to them and requested them to return immediately from whence they came however all our endeavors proved fruitless, I could not prevent them from camping round the Fort-they have caught the disease, notwithstanding I have never allowed an Indian to enter the Fort, or any communication between them & the Sick; but I presume the air was infected with it for a half mile..."[19] Later, a longboat was sent to Fort McKenzie via the Marias River.
In the end, it is estimated that two-thirds of the Blackfoot population died, along with half of the Assiniboine and Arikara, a third of the Crow, and a quarter of the Pawnee.
[7] Vaccination performed by Hudson Bay Company workers and trained Indigenous people were critical to limiting the spread of smallpox in Canada.
[8] After the epidemic, the Hudson Bay Company implemented a territory wide vaccination program which further reduced smallpox deaths.
More recent scholarship from Dashuk, whose work on Indigenous relations in western Canada is not afraid to criticize European settlers and corporations, argues the spread of smallpox between 1836 and 1840 was unintentional.
[2] Regarding land above the 49th Parallel, as has been shown in this article, the Hudson's Bay Company's response was critical to limiting the epidemic after its outbreak.
Yet in light of all the deaths, the almost complete annihilation of the Mandans, and the terrible suffering the region endured, the label criminal negligence is benign, hardly befitting an action that had such horrendous consequences.
"[21] Another frequently recounted story is that an Indian sneaked aboard the St. Peter and stole a blanket from an infected passenger, thus starting the epidemic.
The many variations of this account have also been criticized by both historians and contemporaries as fiction; a fabrication intended to assuage the guilt of white settlers.
In the nineteenth century, the U. S. Army sent contaminated blankets to Native Americans, especially Plains groups, to control the Indian problem.
After losing his wife and children to smallpox, and acquiring the affliction himself, he gave his final speech to the Arikara and Mandan tribes imploring them to "rise all together and not leave one of them alive", before dying on July 30, 1837.