# Relationship history for MSHA mine 3604943

Current hierarchy: **Keystone Coal Company → Lobb Mining Company → Lobb Mining Company - Hall Job**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** S & D Trucking Company → Lobb Mining Company - Hall Job; 1974-02-15 to 1975-04-01; source msha-controller-operator-history
- **controller_controls_mine:** S & D Trucking Company → Lobb Mining Company - Hall Job; 1974-02-15 to 1975-04-01; source msha-controller-operator-history
- **controller_controls_operator:** S & D Trucking Company → S & D Trucking Company; 1974-02-15 to 1975-04-01; source msha-controller-operator-history
- **operator_operates_mine:** Halfway Coal Yard Inc → Lobb Mining Company - Hall Job; 1975-04-02 to 1985-01-28; source msha-controller-operator-history
- **controller_controls_mine:** Warner Company → Lobb Mining Company - Hall Job; 1975-04-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Warner Company → Halfway Coal Yard Inc; 1975-04-02 to 1985-01-28; source msha-controller-operator-history
- **operator_operates_mine:** Lobb Mining Company → Lobb Mining Company - Hall Job; 1985-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Keystone Coal Company → Lobb Mining Company - Hall Job; 1985-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Keystone Coal Company → Lobb Mining Company; 1985-01-29 to current/open; source msha-controller-operator-history