limited. In the 1940s, planners considered building the Alaska Highway along the Rocky Mountain Front in British Columbia and Alberta but ultimately decided on a coastal route. In the early 2000s, the Nature Conservancy was working to secure environmental easements along the front in Alberta to protect grizzly bear habitat. Montana The Rocky Mountain Front in Montana from the Canada–US border south to about Helena is heavily deformed by faulting, folding, and overthrusting. During the Sevier orogeny mountain-building event about 115 and 55 million years ago, what is known as the Cordilleran foreland thrust-and-fold event occurred along the east side of the Rocky Mountains in northwest Montana. The thrust-and-fold belt does not extend all the way south through Montana. Instead, it cuts west above Three Forks continues south—crossing the Snake River Plain and skirting the west side of the Colorado Plateau before cutting west again to enter California. Although most of this mountain-building has since been obliterated by additional orogeny and volcanic activity, most of it still exists in northwestern Montana. The Rocky Mountain Front in this area represents some of the highest changes of elevation within a short distance anywhere in North America. Much of this part of the front, including the Lewis Range and Livingston Range, have suffered heavy glaciation. According to a definition used by the Christian Science Monitor, the Rocky Mountain Front in Montana extends only about south of the state's northern border. But professors Tony Prato and Dan Fagre define the front in Montana as being wide and long. Ranches cover much of the Rocky Mountain Front in Montana. The spectacular scenery also led to the creation of a number of guest ranches in the area, and some of the state's best-known guest ranches are near Choteau and Augusta. The Rocky Mountain Front in Montana contains some of the last relatively untouched native prairies in the northern Great Plains. The front forms the eastern boundary of what is called the "Crown of the Continent Ecosystem". This area of Montana is prime habitat for wildlife, including the black bear, cougar, deer, elk, grizzly bear, lynx, moose, wolf, and wolverine. It is one of the few places in North America where grizzly bear habitat still extends onto the prairie. Extensive numbers of prairie rattlesnake are also found there. Heavy coal, oil, and natural gas development along the Rocky Mountain Front in Montana began in the 1970s. By