# Relationship history for MSHA mine 3607150

Current hierarchy: **Daugherty Wayne R → Keystone Mining Company Inc → No 1 Strip**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Keystone Mining Company Inc → No 1 Strip; 1981-06-01 to 1982-07-05; source msha-controller-operator-history
- **controller_controls_mine:** Hudach Fred → No 1 Strip; 1981-06-01 to 1982-07-05; source msha-controller-operator-history
- **controller_controls_operator:** Hudach Fred → Keystone Mining Company Inc; 1981-06-01 to 1982-07-05; source msha-controller-operator-history
- **operator_operates_mine:** Keystone Mining Company Inc → No 1 Strip; 1982-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Daugherty Wayne R → No 1 Strip; 1982-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Daugherty Wayne R → Keystone Mining Company Inc; 1982-07-06 to current/open; source msha-controller-operator-history