William Griffioen has 4 recorded races from Chicago, Illinois, US.
| Date | Race | Distance | Time | Overall |
|---|---|---|---|---|
| 2025-08-23 | 2025 Chicago Triathlon Olympic | Ultra Marathon | 3:29:54 | 1984 |
| 2024-08-24 | 2024 Chicago Triathlon International | Ultra Marathon | 3:31:25 | 1800 |
| 2023-08-27 | 2023 Chicago Triathlon International | Ultra Marathon | 2:29:22 | 1222 |
| 2022-08-28 | 2022 Chicago Triathlon International - Individual | Ultra Marathon | 3:16:34 | 1418 |