# Relationship history for MSHA mine 3303590

Current hierarchy: **BHP Billiton → Hanging Rock Dock Company → Hanging Rock Dock**

- 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:** Superior River Coal Corp → Hanging Rock Dock; 1977-03-01 to 1980-02-11; source msha-controller-operator-history
- **controller_controls_mine:** Sigmon Harold A → Hanging Rock Dock; 1977-03-01 to 1980-02-11; source msha-controller-operator-history
- **controller_controls_operator:** Sigmon Harold A → Superior River Coal Corp; 1977-03-01 to 1980-02-11; source msha-controller-operator-history
- **operator_operates_mine:** A B C Dock Inc → Hanging Rock Dock; 1980-02-12 to 1983-08-10; source msha-controller-operator-history
- **controller_controls_mine:** Mc Coy Henry M → Hanging Rock Dock; 1980-02-12 to 1983-08-10; source msha-controller-operator-history
- **controller_controls_operator:** Mc Coy Henry M → A B C Dock Inc; 1980-02-12 to 1983-08-10; source msha-controller-operator-history
- **operator_operates_mine:** Hanging Rock Coal Inc → Hanging Rock Dock; 1983-08-11 to 1984-04-17; source msha-controller-operator-history
- **controller_controls_mine:** Click John R → Hanging Rock Dock; 1983-08-11 to 1984-04-17; source msha-controller-operator-history
- **controller_controls_operator:** Click John R → Hanging Rock Coal Inc; 1983-08-11 to 1984-04-17; source msha-controller-operator-history
- **operator_operates_mine:** Hanging Rock Dock Company → Hanging Rock Dock; 1984-04-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** BHP Billiton → Hanging Rock Dock; 1984-04-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** BHP Billiton → Hanging Rock Dock Company; 1984-04-18 to current/open; source msha-controller-operator-history