# Relationship history for MSHA mine 3304124

Current hierarchy: **Stewart Walter → Stewart Construction Company → Blackfork 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

- **controller_controls_mine:** Phil A  Bowman  et al → Blackfork Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stewart Walter → Blackfork Mine; 1975-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Waterloo Coal Company → Blackfork Mine; 1987-12-01 to 1988-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Phil A  Bowman  et al → Waterloo Coal Company; 1987-12-01 to 1988-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Waterloo Coal Company Inc → Blackfork Mine; 1988-10-01 to 1989-01-02; source msha-controller-operator-history
- **controller_controls_mine:** Theodore L  Darlington → Blackfork Mine; 1988-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Theodore L  Darlington → Waterloo Coal Company Inc; 1988-10-01 to 1989-01-02; source msha-controller-operator-history
- **operator_operates_mine:** Stewart Construction Company → Blackfork Mine; 1989-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stewart Walter → Stewart Construction Company; 1989-01-03 to current/open; source msha-controller-operator-history