# Relationship history for MSHA mine 1509707

Current hierarchy: **Harbert Construction Corp → Nu Don Coal Company Inc → No 1 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

- **operator_operates_mine:** Nu Don Coal Company Inc → No 1 Mine; 1976-06-02 to 1976-08-31; source msha-controller-operator-history
- **controller_controls_mine:** Brownies Creek Collieries Inc → No 1 Mine; 1976-06-02 to 1976-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Brownies Creek Collieries Inc → Nu Don Coal Company Inc; 1976-06-02 to 1976-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Nu Don Coal Company Inc → No 1 Mine; 1976-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harbert Construction Corp → No 1 Mine; 1976-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harbert Construction Corp → Nu Don Coal Company Inc; 1976-09-01 to current/open; source msha-controller-operator-history