# Relationship history for MSHA mine 1201527

Current hierarchy: **Zirkle William → Arco Engineering Construction Corp → Arco 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:** Indiana Highway Materials Inc → Arco Pit; 1950-01-01 to 1983-07-11; source msha-controller-operator-history
- **controller_controls_mine:** Zirkle Keith → Arco Pit; 1950-01-01 to 1983-07-11; source msha-controller-operator-history
- **controller_controls_operator:** Zirkle Keith → Indiana Highway Materials Inc; 1950-01-01 to 1983-07-11; source msha-controller-operator-history
- **operator_operates_mine:** Arco Engineering Construction Corp → Arco Pit; 1983-07-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zirkle William → Arco Pit; 1983-07-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zirkle William → Arco Engineering Construction Corp; 1983-07-12 to current/open; source msha-controller-operator-history