Historical documents are ambiguous regarding the presence/absence and distribution of pronghorn (Antilocapra americana) in eastern Washington State. Paleozoological (archaeological and paleontological) data indicate pronghorn were present there during most of the last 10,000 years, and available samples imply the boundaries of pronghorn distribution coincided with the modern distribution of shrub-steppe habitats. There is no evidence of temporal fluctuation in the abundance of pronghorn that cannot be explained by sampling error. Pronghorn were abundant relative to wapiti (Cervus elaphus) at the mouth of the Snake River but rare near the Washington–Idaho border. Pronghorn were never abundant relative to other ungulates, but were occasionally sufficiently numerous to form herds that were taken communally by groups of prehistoric hunters. Pronghorn were present but rare in the nineteenth century and did not persist into the twentieth century.