Leaving Denver at sunrise this morning, I headed north on Interstate 25, passing the snowy peaks of the Front Range and undulating across the Piedmont, dipping to cross tributaries of the South Platte River. Approaching the Wyoming line, the highway climbs onto the Gangplank, leaving the watershed of the South Platte and then gradually dropping into the North Platte Basin. After descending through the Chugwater River Canyon, lined with flat-topped escarpments, I-25 passes Wheatland, where the traveler enjoys a spectacular view of the Laramie Mountains to the west, dominated by Laramie Peak; a few miles north of that city, the highway crosses the Laramie River, a major tributary of the North Platte (which is eventually crossed at Orin, at Douglas and at Casper).
Angling westward at Douglas, I-25 parallels the North Platte (as it flows eastward) and curves along the north end of the Laramie Mountains. At Casper, it leaves the river and leads north; halfway to Buffalo, the highway crosses a low divide, leaving the North Platte watershed and entering the Powder River Basin. Here the greenery increases dramatically and herds of sheep join native pronghorn on the lush hillsides. Nearing Kaycee, the southern end of the Bighorn Range looms west of the Interstate, which crosses the three upper forks of the Powder River; farther along, I-25 also crosses forks of the Crazy Woman River. Low clouds and heavy rain limited views of the Bighorn Range between Buffalo and Sheridan but the sun returned as I reached the Montana line and the north end of the Bighorns towered to the west. Before reaching Billings, the highway (now I-90) crosses both the historically famous Little Bighorn and the Bighorn Rivers, both tributaries of the Yellowstone River.
At Billings, I drove westward on I-90 through the Yellowstone River Valley. Before long, the Absaroka Range appeared to the WSW and the Crazy Mountains gleamed from the WNW; the highway eventually passes between these scenic massifs, following the Yellowstone to Livingston, where the river flows down from Yellowstone National Park. I'll spend the night in that town before making my circuit through southwestern Montana.
