Mark Williamson has 3 recorded races from Grand Rapids, Michigan, US.
| Date | Race | Distance | Time | Overall |
|---|---|---|---|---|
| 2025-08-23 | 2025 Chicago Triathlon Sprint | 1:51:45 | 816 | |
| 2024-08-24 | 2024 Chicago Triathlon Sprint | 2:08:33 | 1175 | |
| TCS London Marathon 2023 | Marathon | 3:49:36 | 14315 |