# Relationship history for MSHA mine 2100209

Current hierarchy: **Cleveland-Cliffs Inc → Northshore Mining Company → Northshore Mining Company**

- 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:** Reserve Mining Company → Northshore Mining Company; 1950-01-01 to 1989-08-31; source msha-controller-operator-history
- **controller_controls_mine:** L T V Steel Corp et al → Northshore Mining Company; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** L T V Steel Corp et al → Reserve Mining Company; 1950-01-01 to 1989-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Armco Inc et al → Reserve Mining Company; 1950-01-01 to 1989-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Cyprus Northshore Mining Corp → Northshore Mining Company; 1989-09-01 to 1994-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Cyprus Amax Minerals Company → Northshore Mining Company; 1989-09-01 to 1994-09-30; source msha-controller-operator-history
- **controller_controls_operator:** Cyprus Amax Minerals Company → Cyprus Northshore Mining Corp; 1989-09-01 to 1994-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Northshore Mining Company → Northshore Mining Company; 1994-10-01 to 2008-05-13; source msha-controller-operator-history
- **controller_controls_mine:** Cliffs Minnesota Minerals Company → Northshore Mining Company; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cliffs Minnesota Minerals Company → Northshore Mining Company; 1994-10-01 to 2008-05-13; source msha-controller-operator-history
- **operator_operates_mine:** Northshore Mining Company → Northshore Mining Company; 2008-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cleveland-Cliffs Inc → Northshore Mining Company; 2008-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cleveland-Cliffs Inc → Northshore Mining Company; 2008-05-14 to current/open; source msha-controller-operator-history