Midway between Casper and Douglas along the south bank of the North Platte River, Glenrock (pop. 2,598) was a vital rest stop and supply station on the Oregon and other emigrant trails. Several downtown buildings have endured since its heyday, when Glenrock was known as Deer Creek Station and some 20,000 migrants came through each year, many of them camping overnight at the “rock in the glen” on the west side of town, where a sandstone boulder still holds the names of passing pioneers. Nowadays, Glenrock is known for its massive 800-megawatt coal-fired power plant, one of the largest in the country; a pair of wind farms intended to generate 100 megawatts of electricity are under construction nearby.

Between Casper and Glenrock, US-26 winds along the river, but between Glenrock and Douglas the old road has been replaced by the I-25 freeway. A dozen miles east of Glenrock, midway to Douglas, turn off I-25 onto Natural Bridge Road and drive five miles south of the freeway to visit one of Wyoming’s unsung beauty spots, Ayres Natural Bridge, which arches 30 feet above peaceful La Prele Creek, next to a small campground in a pleasant county park.