# Relationship history for MSHA mine 1507085

Current hierarchy: **Ball & Smith Coal Co → Ball & Smith Coal Co → 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:** W B & W Coal Co → No 1 Mine; 1974-01-01 to 1974-08-29; source msha-controller-operator-history
- **controller_controls_mine:** W B & W Coal Co → No 1 Mine; 1974-01-01 to 1974-08-29; source msha-controller-operator-history
- **controller_controls_operator:** W B & W Coal Co → W B & W Coal Co; 1974-01-01 to 1974-08-29; source msha-controller-operator-history
- **operator_operates_mine:** Ball & Smith Coal Co → No 1 Mine; 1974-08-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ball & Smith Coal Co → No 1 Mine; 1974-08-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ball & Smith Coal Co → Ball & Smith Coal Co; 1974-08-30 to current/open; source msha-controller-operator-history