Yellowstone National Park Northern Boundary & Entrance Gate Wyoming / Montana State Line. North to community of Gardiner 0.5 miles. Welcome to Montana. Start / Finish of Highway Travel Guide YELLOWSTONE NATIONAL PARK - Madison to Mammoth Hot Springs - Montana / Wyoming State Line With half of the earth’s geothermal features, Yellowstone holds the planet’s most diverse and intact collection of geysers, hot springs, mudpots, and fumaroles. Its more than 300 geysers make up two thirds of all those found on earth.