William Clark, of the Lewis and Clark expedition, first saw pronghorn at the eastern edge of their range, near the mouth of the Niobrara River in today's Nebraska, on September 6, 1804. He wrote, "They are all keenly made, and is butifull." Meriwether Lewis was no less impressed. In mid-July at the Great Falls in Montana he wrote that, "they appear very inquisitive, usually to learn what we are as we pass, and frequently accompany us at no great distance for miles, frequently halting and giving a loud whistle through their nostrils. They are a very pretty animal, and astonishingly fleet and active."
Around 1850 there were still perhaps 40 to 50 million pronghorns in western North America, but by 1920 the population had dropped to around 13,000, owing to the expansion of farms and ranches. Today, as a result of intensive wildlife management policies and landowner cooperation, there are an estimated 450,000 pronghorns roaming parts of the Western plains. However, some sub-species remain endangered.