| Mark | Athlete | School | Year | Meet |
|---|
| 58.29 | Paige Harris | Plentywood (B) | 12 | State C |
| 58.80 | Kim Parsell | Shelby (B) | 12 | MHSA Class B Championships |
| 59.34 | Payton Durocher | Choteau (B) | 11 | MHSA Class B Championships |
| 59.55 | Haile Norred | Bigfork (B) | 10 | Archie Roe Invitational |
| 59.87 | Alexa Arthun | Manhattan (B) | 11 | Butte Invite |
| 1:00.75 | Caitlin Hoeffner | Broadwater/Townsend (B) | 12 | MHSA Class B Championships |
| 1:00.76 | Mattison McAnaly | Bigfork (B) | 12 | MHSA Class B Championships |
| 1:01.18 | Alex Simensen | Glasgow (B) | 12 | MHSA Class B Championships |
| 1:01.29 | Scotti Robinson | Baker (B) | 11 | MHSA Class B Championships |
| 1:01.98 | Savannah Stern | Choteau (B) | 11 | MHSA Class B Championships |
| 1:02.00 | Autumn Round | Florence-Carlton (B) | 11 | MHSA Class B Championships |
| 1:02.00 | Bryn Morley | Bigfork (B) | 10 | Eureka Invitational |