# Relationship history for MSHA mine 4403721

Current hierarchy: **Clark Douglas P & Frank D → C B C Coal Company → No 1 Mine**

- 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:** Four H Coal Company Inc → No 1 Mine; 1974-01-01 to 1977-04-12; source msha-controller-operator-history
- **controller_controls_mine:** William P  Harris et al → No 1 Mine; 1974-01-01 to 1977-04-12; source msha-controller-operator-history
- **controller_controls_operator:** William P  Harris et al → Four H Coal Company Inc; 1974-01-01 to 1977-04-12; source msha-controller-operator-history
- **operator_operates_mine:** Standard Coal Company → No 1 Mine; 1977-04-13 to 1977-08-04; source msha-controller-operator-history
- **controller_controls_mine:** Wright Larry → No 1 Mine; 1977-04-13 to 1977-08-04; source msha-controller-operator-history
- **controller_controls_operator:** Wright Larry → Standard Coal Company; 1977-04-13 to 1977-08-04; source msha-controller-operator-history
- **operator_operates_mine:** C B C Coal Company → No 1 Mine; 1977-08-05 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Clark Douglas P & Frank D → No 1 Mine; 1977-08-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clark Douglas P & Frank D → C B C Coal Company; 1977-08-05 to current/open; source msha-controller-operator-history