This backyard ultra takes place at Dry Creek Parkway, in Sacramento, California.

In the traditional style, runners will have one hour to complete each 4.16 mile loop. Each new yard (loop) will begin every hour, on the hour. If a runner is not in the start corral, ready to begin the next yard, on the hour mark, they’re out. The runner who completes the most yards wins.

B.A.B.U. was originally created in 2023 as a fatass event. In 2024 it was made an official event as a collaboration between Skybreaker Racing and Auburn Area Trail Runners. Today, while the event is still put on by the same organizers, through partnership, B.A.B.U. is now under the Singletrack Running umbrella.