Interstate 90 generally follows the Yellowstone River from Glendive to Livingston, Montana. The river originates south of Yellowstone National Park and ends where it joins the Missouri River north of here. It is the longest undammed river in the lower 48 states. While most rivers in the American West were dammed and dewatered, the Yellowstone remains wet, wild, and dam-free over its entire length. It flows free for over 650 miles and drains a watershed larger than all the New England states combined. In the 1970s, Montana debated the river's future and ultimately reserved a substantial amount of water to remain in the stream so the Yellowstone would not be depleted and could remain free-flowing, while also providing for municipal, agricultural, and industrial uses. Today the river remains a balance among all its users, including nature's creatures, a claim few American rivers can still make.