from nvexpeditions.com:
Riverside was the location of a service station established by Carl Enkey around 1930 to serve travelers on Highway 91. Before 1925, the Arrowhead Trail (US-91) followed a southerly route to St. Thomas, but loss of a major bridge to fire coupled with the impending construction of Hoover Dam (and subsequent loss of St. Thomas) prompted construction of a new, more northern route that closely parallels today’s Interstate 15.

Riverside appears to have had cabins, presumably for lodging, in addition to the service station, and possibly a few homes. It was probably closed around 1955, when the highway was rerouted and bypassed the communities of the Virgin River Valley. A handful of buildings remained until they were bulldozed in February 2025.