# Relationship history for MSHA mine 3303822

Current hierarchy: **Compass International Corp → Horizon Coal Corp → Horizon Strip - Morton**

- 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:** U S Filter Corp → Horizon Strip - Morton; 1976-11-01 to 1981-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Horizon Coal Corp → Horizon Strip - Morton; 1980-07-01 to 1981-03-31; source msha-controller-operator-history
- **controller_controls_operator:** U S Filter Corp → Horizon Coal Corp; 1980-07-01 to 1981-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Horizon Coal Corp → Horizon Strip - Morton; 1981-04-01 to 1982-11-21; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc et al → Horizon Strip - Morton; 1981-04-01 to 1982-12-16; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc et al → Horizon Coal Corp; 1981-04-01 to 1982-11-21; source msha-controller-operator-history
- **operator_operates_mine:** Horizon Coal Corp → Horizon Strip - Morton; 1982-11-22 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Compass International Corp → Horizon Strip - Morton; 1982-11-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Compass International Corp → Horizon Coal Corp; 1982-11-22 to current/open; source msha-controller-operator-history