At 65, Susannah Dyson, an electrical engineer by profession, recently ran more than 66 miles during a backyard ultramarathon outside Indianapolis, marking her longest distance to date. The Prairie on Fire backyard ultra, held last month, challenged participants to complete a 4.167-mile loop every hour, continuing until only one runner remained.

Backyard ultramarathons require participants to finish the same lap within the hour; completing it early allows for rest before the next lap begins, but failing to finish means elimination. These races can extend over several days and often cover distances exceeding 100 miles. The current world record, set in Australia last year, stands at nearly 500 miles.

Despite the grueling nature of the format, backyard ultramarathons have experienced significant growth. Over the past year, at least 500 such races took place globally, with more than 700 scheduled for the coming year. These events occur in diverse settings, including parking lots and multi-use trails across the United States and approximately 80 other countries.

This year’s Prairie on Fire attracted several hundred runners, primarily from the local area, many accompanied by friends and family who provided support. Participants set up tents and resting areas along the course, running repeatedly until they could no longer continue. Dyson described the experience as rewarding despite the physical toll the following day.

The backyard ultramarathon concept traces back to 2011 when Gary “Lazarus Lake” Cantrell—known for organizing the Barkley Marathons, an ultradistance race completed by only 20 runners since 1995—created the first backyard ultra on his 140-acre farm. Cantrell noted that the race’s rapid expansion in popularity was unexpected. He attributes its appeal to the pacing style, which is slower than many marathon cutoffs, allowing runners to sustain their effort for longer periods. The hourly rest intervals also foster a social atmosphere uncommon in traditional ultramarathons, where competitors often race in isolation.

Compared to other ultramarathons, which frequently take place in remote and logistically complex environments such as the Rocky Mountains, backyard ultras are simpler to organize and execute. This accessibility contributed to their rise during the COVID-19 pandemic, when socially distanced virtual races became common. Prairie on Fire’s organizer, TJ Dailey, initially hosted a virtual event in 2022 with 15 participants; this year saw a major increase, with 228 runners completing at least one lap and 117 surpassing 50 miles.

Dailey likened the event’s tent city to the ephemeral community of the Burning Man festival, characterizing it as a temporary gathering for individuals seeking an intense and immersive experience outside daily life. The race commenced with a Viking chant adapted from the Norwegian World Cup team, progressing at a near-walking pace before runners settled into varied strategies balancing speed and rest. Some runners prioritize energy conservation to maximize rest time, while others pace faster for additional breaks or sleep.

Throughout the event, competitors manage nutrition, hydration, and physical endurance, pushing themselves until mental or physical limits force withdrawal. The backyard ultramarathon’s combination of endurance challenge, community atmosphere, and straightforward logistics continues to attract a diverse field of runners from around the world.