# Relationship history for MSHA mine 1505476

Current hierarchy: **Elswick Curtis & Son Coal Company → Curtis Elswick & Son Coal Co → No 1 Surface**

- 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:** Curtis Elswick & Son Coal Co → No 1 Surface; 1950-01-01 to 1974-11-14; source msha-controller-operator-history
- **controller_controls_mine:** Elswick Curtis & Son Coal Company → No 1 Surface; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Elswick Curtis & Son Coal Company → Curtis Elswick & Son Coal Co; 1950-01-01 to 1974-11-14; source msha-controller-operator-history
- **operator_operates_mine:** Dry Fork Fuel Company → No 1 Surface; 1974-11-15 to 1975-06-25; source msha-controller-operator-history
- **controller_controls_mine:** Ratliff Donald E → No 1 Surface; 1974-11-15 to 1975-06-25; source msha-controller-operator-history
- **controller_controls_operator:** Ratliff Donald E → Dry Fork Fuel Company; 1974-11-15 to 1975-06-25; source msha-controller-operator-history
- **operator_operates_mine:** Curtis Elswick & Son Coal Co → No 1 Surface; 1975-06-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Elswick Curtis & Son Coal Company → Curtis Elswick & Son Coal Co; 1975-06-26 to current/open; source msha-controller-operator-history