| Mark | Athlete | School | Year | Meet |
|---|
| 42.86 | Liz Harper | Missoula Sentinel (AA) | 11 | Western AA Divisional |
| 43.22 | Tess Brenneman | Flathead (AA) | 12 | Western AA Divisional |
| 44.78 | Morgan Sulser | Billings Senior (AA) | 10 | State AA Track Meet |
| 45.47 | Allison Morrison | Helena (AA) | 12 | Western AA Divisional |
| 46.14 | Lexy Boschee | Glacier (AA) | 12 | Whitefish A.R.M. Invitational |
| 46.18 | Shelby Erdahl | Belgrade (AA) | 12 | Gallatin Valley Invitational |
| 47.14 | Alyssa Espinoza | Billings West (AA) | 11 | Billings City Meet |
| 47.17 | Hailey Gellner | Billings Skyview (AA) | 10 | Billings Invitational |
| 47.51 | Natalie Zimmer | Missoula Big Sky (AA) | 12 | Western AA Divisional |
| 47.60 | Tori Nickol | Helena Capital (AA) | 12 | Western AA Divisional |
| 47.71 | Kwyn Johnson | Flathead (AA) | 11 | Libby-Flathead Dual |
| 47.86 | Brianna Olson | Missoula Sentinel (AA) | 11 | Western AA Divisional |
| 47.95 | Jordan Dreessen | Billings Senior (AA) | 12 | 5-5 Billings West Triangular |
| 48.25 | Tori Weyand | Billings West (AA) | 12 | Eastern AA Divisional |
| 48.34 | Courtney Carl | Missoula Big Sky (AA) | 9 | Western AA Divisional |
| 48.91 | Mattie Mazur | Flathead (AA) | 10 | Optimist Track Meet |
| 48.93 | Rhiannon Sturgess | Flathead (AA) | 10 | Western AA Divisional |
| 48.93 | Bethany Norby | Billings Senior (AA) | | State A Track Meet |
| 48.95 | Alison Lunde | Flathead (AA) | 12 | Western AA Divisional |
| 48.95 | Terra McDowell | Billings Senior (AA) | 12 | State AA Track Meet |