Backyard Ultra races are last-person-standing ultraruns where runners complete repeating loops until only one remains. The examples provided are smaller, local instances of this format: the Bullshit Backyard Ultra in Lenoxville, Pennsylvania, the Capital Backyard Ultra in Lorton, Virginia, and Ohio's Backyard Ultra at McChesney Ridge Athletic Club in Lucasville, Ohio.
Capital limits its field to 60 runners and employs two loops: a daytime route on horse trails through open fields, dirt, and crushed gravel, followed by a nighttime route on a paved bike path. The day loop ascends approximately 300 to 350 feet per lap, while the night loop is rolling but largely flat with about 75 feet of elevation change. Ohio's race caps its field at 115, typically sells out quickly, and can fill in as little as 20 minutes, although waitlisted participants might still be admitted on race morning.