# Relationship history for MSHA mine 1508458

Current hierarchy: **Blair Ernest → Blair Coal Company Inc → No H-1**

- 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

- **controller_controls_mine:** James W  Potter et al → No H-1; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Derek  Potter et al → No H-1; 1950-01-01 to 1977-10-02; source msha-controller-operator-history
- **operator_operates_mine:** Potter Mining Company Inc → No H-1; 1975-06-23 to 1976-01-28; source msha-controller-operator-history
- **controller_controls_operator:** James W  Potter et al → Potter Mining Company Inc; 1975-06-23 to 1976-01-28; source msha-controller-operator-history
- **operator_operates_mine:** Crystal Coal Corp Inc → No H-1; 1976-01-29 to 1977-02-10; source msha-controller-operator-history
- **controller_controls_operator:** Derek  Potter et al → Crystal Coal Corp Inc; 1976-01-29 to 1977-02-10; source msha-controller-operator-history
- **operator_operates_mine:** Blair Coal Company Inc → No H-1; 1977-02-11 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Blair Ernest → No H-1; 1977-02-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blair Ernest → Blair Coal Company Inc; 1977-02-11 to current/open; source msha-controller-operator-history