# Relationship history for MSHA mine 3400028

Current hierarchy: **Lone Star Industries Inc → Oklahoma Cement → Pryor Mill**

- 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:** Okc Corp → Pryor Mill; 1950-01-01 to 1980-06-17; source msha-controller-operator-history
- **controller_controls_mine:** OKC Corp → Pryor Mill; 1950-01-01 to 1980-10-19; source msha-controller-operator-history
- **controller_controls_operator:** OKC Corp → Okc Corp; 1950-01-01 to 1980-06-17; source msha-controller-operator-history
- **operator_operates_mine:** Oklahoma Cement → Pryor Mill; 1980-06-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lone Star Industries Inc → Pryor Mill; 1980-06-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lone Star Industries Inc → Oklahoma Cement; 1980-06-18 to current/open; source msha-controller-operator-history