# Relationship history for MSHA mine 3607531

Current hierarchy: **Kroh Richard & Dave Brown → K & B Coal Company → No 1 Drift**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** K & P Coal Company → No 1 Drift; 1984-01-01 to 1985-11-24; source msha-controller-operator-history
- **controller_controls_mine:** Knorr Leroy Et Al → No 1 Drift; 1984-01-01 to 1985-11-24; source msha-controller-operator-history
- **controller_controls_operator:** Knorr Leroy Et Al → K & P Coal Company; 1984-01-01 to 1985-11-24; source msha-controller-operator-history
- **operator_operates_mine:** K & B Coal Company → No 1 Drift; 1985-11-25 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kroh Richard & Dave Brown → No 1 Drift; 1985-11-25 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kroh Richard & Dave Brown → K & B Coal Company; 1985-11-25 to current/open; source msha-controller-operator-history