# Relationship history for MSHA mine 1508173

Current hierarchy: **Huffman Bruce → B Huffman Mining Company → Prep 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Branham Bill T & Dr William C Ratliff → Prep Plant; 1974-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dunleary Elkhorn Coal Co → Prep Plant; 1975-01-01 to 1977-10-11; source msha-controller-operator-history
- **controller_controls_operator:** Branham Bill T & Dr William C Ratliff → Dunleary Elkhorn Coal Co; 1975-01-01 to 1977-10-11; source msha-controller-operator-history
- **operator_operates_mine:** B Huffman Mining Company → Prep Plant; 1977-10-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Huffman Bruce → Prep Plant; 1977-10-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Huffman Bruce → B Huffman Mining Company; 1977-10-12 to current/open; source msha-controller-operator-history