Ayres Natural Bridge Park, County park in Converse County, Wyoming, US.

Ayres Natural Bridge Park is a 150-acre county park whose centrepiece is Ayres Natural Bridge, a 30-foot-high, 50-foot-wide arch of Casper Formation sandstone over LaPrele Creek. The arch has two rocky abutments, a dark horizontal opening beneath it, and an uneven top covered with trees and shrubs; a small stone structure sits against the upper left rock face.

Alvah W. Ayres settled the ranch around 1882, and his son Andrew C. Ayres deeded the land to Converse County in May 1920. Emigrants on the Oregon Trail, about a mile south, had visited the bridge since the 1840s; a pioneer in 1843 called it "a natural bridge of solid rock, over a rapid torrent, the arch being regular as tho' shaped by art."

The Arapaho and other Plains peoples avoided the bridge, believing an evil spirit lived beneath it after a warrior was struck by lightning there. Settlers on the Oregon Trail, about two miles away, camped at the bridge for safety from attacks. The park's name honors Alvah W. Ayres, who settled around 1882; his son Andrew C. Ayres deeded the land to Converse County in May 1920.

The park lies between Glenrock and Douglas, about 6 km south of Interstate 25 exit 151, and is open from April 15 to October 15, 8 a.m. to 8 p.m.; registered campers may stay overnight. There is a small campground, open picnic areas with covered tables, and a playground. Pets are not allowed anywhere in the park.

The arch was carved by a bend in LaPrele Creek, once called Bridge Creek, which cut through a wall of Casper Formation sandstone until it broke through and straightened its course. Alvah W. Ayres settled here around 1882, and his son Andrew C. Ayres deeded the land to Converse County in May 1920.