# Relationship history for MSHA mine 1800121

Current hierarchy: **Thrasher James D → Thrasher Coal Company → 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:** J R Thrasher Contracting & Stripping Co → No 1 Strip; 1950-01-01 to 1976-10-31; source msha-controller-operator-history
- **controller_controls_mine:** Thrasher J R → No 1 Strip; 1950-01-01 to 1976-10-31; source msha-controller-operator-history
- **controller_controls_operator:** Thrasher J R → J R Thrasher Contracting & Stripping Co; 1950-01-01 to 1976-10-31; source msha-controller-operator-history
- **operator_operates_mine:** Thrasher Coal Company → No 1 Strip; 1976-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thrasher James D → No 1 Strip; 1976-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thrasher James D → Thrasher Coal Company; 1976-11-01 to current/open; source msha-controller-operator-history