# Relationship history for MSHA mine 3500052

Current hierarchy: **Ash Grove Cement Company → Ash Grove Cement West Inc → Durkee Cement Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Oregon Portland Cement Company → Durkee Cement Plant; 1950-01-01 to 1983-12-18; source msha-controller-operator-history
- **controller_controls_mine:** Oregon Portland Cement Company → Durkee Cement Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Oregon Portland Cement Company → Oregon Portland Cement Company; 1950-01-01 to 1983-12-18; source msha-controller-operator-history
- **controller_controls_mine:** Ash Grove Cement Company → Durkee Cement Plant; 1983-08-24 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ash Grove Cement West Inc → Durkee Cement Plant; 1983-12-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ash Grove Cement Company → Ash Grove Cement West Inc; 1983-12-19 to current/open; source msha-controller-operator-history