# Relationship history for MSHA mine 4201944

Current hierarchy: **Berkshire Hathaway Inc → Interwest Mining Company → Cottonwood Mine**

- 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:** Savage Companies → Cottonwood Mine; 1979-03-21 to 1986-04-27; source msha-controller-operator-history
- **operator_operates_mine:** Emery Mining Corp → Cottonwood Mine; 1985-06-01 to 1986-04-27; source msha-controller-operator-history
- **controller_controls_operator:** Savage Companies → Emery Mining Corp; 1985-06-01 to 1986-04-27; source msha-controller-operator-history
- **operator_operates_mine:** Energy West Mining Company → Cottonwood Mine; 1986-04-28 to 2015-10-05; source msha-controller-operator-history
- **controller_controls_mine:** MidAmerican Energy Holdings Company → Cottonwood Mine; 1986-04-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MidAmerican Energy Holdings Company → Energy West Mining Company; 1986-04-28 to 2015-10-05; source msha-controller-operator-history
- **operator_operates_mine:** Interwest Mining Company → Cottonwood Mine; 2015-10-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Berkshire Hathaway Inc → Cottonwood Mine; 2015-10-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Berkshire Hathaway Inc → Interwest Mining Company; 2015-10-06 to current/open; source msha-controller-operator-history