# Relationship history for MSHA mine 4201870

Current hierarchy: **Carlson Michael → Carlson Construction Inc → Carlson Willard 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:** K D Sand & Gravel Company → Carlson Willard Pit; 1984-03-01 to 1984-08-16; source msha-controller-operator-history
- **controller_controls_mine:** Nielsen Darrell → Carlson Willard Pit; 1984-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nielsen Darrell → K D Sand & Gravel Company; 1984-03-01 to 1984-08-16; source msha-controller-operator-history
- **controller_controls_mine:** Carlson Michael → Carlson Willard Pit; 1984-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Carlson Construction Inc → Carlson Willard Pit; 1984-08-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carlson Michael → Carlson Construction Inc; 1984-08-17 to current/open; source msha-controller-operator-history