# Relationship history for MSHA mine 2000980

Current hierarchy: **Howes Gene → Howes & Howes Trucking Inc → Ellsworth Shale 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Medusa Portland Cement Company → Ellsworth Shale Pit; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Medusa Corp → Ellsworth Shale Pit; 1950-01-01 to 1998-06-29; source msha-controller-operator-history
- **controller_controls_operator:** Medusa Corp → Medusa Portland Cement Company; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Medusa Portland Cement Company → Ellsworth Shale Pit; 1979-01-01 to 1979-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Crane Company → Ellsworth Shale Pit; 1979-01-01 to 1979-06-30; source msha-controller-operator-history
- **controller_controls_operator:** Crane Company → Medusa Portland Cement Company; 1979-01-01 to 1979-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Howes Gene → Ellsworth Shale Pit; 1979-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Howes & Howes Trucking Inc → Ellsworth Shale Pit; 1979-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howes Gene → Howes & Howes Trucking Inc; 1979-07-01 to current/open; source msha-controller-operator-history