# Relationship history for MSHA mine 4607962

Current hierarchy: **Black William E → Ridgeway Development Corp → No 1 Strip**

- 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:** Ridgeway Development Corp → No 1 Strip; 1990-11-01 to 1991-09-16; source msha-controller-operator-history
- **controller_controls_mine:** Henry Dale  Shrewsbury → No 1 Strip; 1990-11-01 to 1991-11-26; source msha-controller-operator-history
- **controller_controls_operator:** Henry Dale  Shrewsbury → Ridgeway Development Corp; 1990-11-01 to 1991-09-16; source msha-controller-operator-history
- **operator_operates_mine:** Ridgeway Development Corp → No 1 Strip; 1991-09-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Black William E → No 1 Strip; 1991-09-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Black William E → Ridgeway Development Corp; 1991-09-17 to current/open; source msha-controller-operator-history