Between 1805, when Meriwether Lewis and William Clark first traversed the continent, and the 1860s, the buffalo's numbers fell from probably 30m-60m to fewer than 15m.
Meriwether Lewis (August 18, 1774 – October 11, 1809) was an American explorer, soldier, politician, and public administrator, best known for his role as the leader of the Lewis and Clark Expedition, also known as the Corps of Discovery, with William Clark.