# Relationship history for MSHA mine 1900928

Current hierarchy: **Dunbar Stephen M → Dunbar Transportation Inc → Townsend Pit**

- 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:** Dunbar Sand & Gravel Corp → Townsend Pit; 1950-01-01 to 1981-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Dunbar Stephen M → Townsend Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dunbar Stephen M → Dunbar Sand & Gravel Corp; 1950-01-01 to 1981-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Townsend Sand & Gravel Inc → Townsend Pit; 1981-07-01 to 1984-10-14; source msha-controller-operator-history
- **controller_controls_mine:** Dunbar Stephen M-Thomas Murray Jr Et Al → Townsend Pit; 1981-07-01 to 1984-10-14; source msha-controller-operator-history
- **controller_controls_operator:** Dunbar Stephen M-Thomas Murray Jr Et Al → Townsend Sand & Gravel Inc; 1981-07-01 to 1984-10-14; source msha-controller-operator-history
- **operator_operates_mine:** Dunbar Transportation Inc → Townsend Pit; 1984-10-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dunbar Stephen M → Townsend Pit; 1984-10-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dunbar Stephen M → Dunbar Transportation Inc; 1984-10-15 to current/open; source msha-controller-operator-history