Regions of Wyoming

Cheyenne sits at 6,062 feet on the last rise of the High Plains, where I-25 and I-80 cross and where the upslope flow off the Front Range dumps its snow. The city takes more spring snow than anywhere else in the state's east, and the ground east of it down the North Platte is the only irrigated farmland Wyoming has.

Casper Mountain rises 3,000 feet straight off the south edge of town, which is why the city can be in rain while the mountain is in a blizzard and why its snow totals never match anyone's expectations. The North Platte runs through the middle of it, and the country north toward the Powder River is some of the windiest ground in the United States.

The Great Divide Basin is the one place in North America where the Continental Divide splits in two and encloses a basin that drains nowhere at all. Nothing that falls inside it leaves. This is the driest, most exposed stretch of I-80 in the country, and the ground blizzards that close it between Rawlins and Rock Springs are the reason the state runs variable-speed gates.

Forty percent of the coal burned in the United States comes out of the ground in these three counties, which makes the Powder River Basin the most consequential piece of weather-exposed industry in the state. The Black Hills rise on the eastern edge at Sundance and Devils Tower, and they are the first thing to catch an upslope storm coming off the plains.

The Bighorn Basin is a desert with mountains on all four sides, and the rain shadow is total: Worland gets under eight inches a year while the Absarokas thirty miles west take forty feet of snow. Everything grown down here is irrigated off that snow, and the Wind River Canyon below Thermopolis is where the river changes its name without changing its water.

This is the wettest and the coldest corner of Wyoming at the same time. The Tetons take 500 inches of snow a year and the valley floors below them hold cold air so well that Jackson and Big Piney trade the state's low temperature most winters. The avalanche forecast here is a daily product, and Togwotee and Teton Pass close on it.

Elk Mountain and Arlington are the single worst stretch of Interstate in the United States for wind: I-80 closes here on ground blizzards under a clear sky, blow-over warnings run most of the winter, and the gates at Laramie and Rawlins exist for this forty miles. The Snowy Range above it holds snow into July, and the Laramie Plains between them sit at 7,200 feet.

The Bighorns rise 8,000 feet off the plain here, and the east slope catches everything that comes at it from the north and east. Sheridan and Buffalo are the wettest towns in eastern Wyoming because of it, and US-16 over Powder River Pass and US-14 over Granite Pass both close for the winter rather than being plowed.

Fremont County is bigger than New Jersey and holds the Wind River Reservation, the Wind River Range and Gannett Peak, the highest ground in Wyoming at 13,809 feet. The range wrings out the westerlies so completely that Dubois at its foot is high desert, and South Pass at the southern end is the low saddle that carried the Oregon, California and Mormon trails over the Divide.