# Relationship history for MSHA mine 4001446

Current hierarchy: **Carson John L & O P Byrd → Carson & Byrd Coal Company → No 1 Mine**

- 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:** Robertson C T → No 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Tenn Tex Coal Corp → No 1 Mine; 1974-01-01 to 1977-02-16; source msha-controller-operator-history
- **controller_controls_operator:** Robertson C T → Tenn Tex Coal Corp; 1974-01-01 to 1977-02-16; source msha-controller-operator-history
- **operator_operates_mine:** Carson & Byrd Coal Company → No 1 Mine; 1977-02-17 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Carson John L & O P Byrd → No 1 Mine; 1977-02-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carson John L & O P Byrd → Carson & Byrd Coal Company; 1977-02-17 to current/open; source msha-controller-operator-history