Ruth Anderson Memorial Endurance Run

The Ruth Anderson Memorial Endurance Run is an ultradistance race held annually in San Francisco, California, at scenic Lake Merced. The course features a mostly flat, USATF-certified 4.48-mile loop around the lake, combining asphalt paths and groomed dirt shoulders with about 100 feet of elevation gain per loop. Runners can choose to compete in 50 kilometers or 50 miles, with aid stations stocked with water, electrolytes, and food available each loop.

The race headquarters at Lake Merced Blvd. and Sunset Blvd. serves as the start, finish, and aid station hub.

The event offers a supportive atmosphere with generous cutoffs and commemorative patches for finishers. Visit the organization's website for the most recent information.