# Relationship history for MSHA mine 3604137

Current hierarchy: **Gulf Usa Corp → C & K Coal Company → Boyers Coal Tipple**

- 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:** Gulf Usa Corp → Boyers Coal Tipple; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Grove City Construction Co → Boyers Coal Tipple; 1950-01-01 to 1974-01-31; source msha-controller-operator-history
- **controller_controls_mine:** Grove City Construction Company → Boyers Coal Tipple; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grove City Construction Company → Grove City Construction Co; 1950-01-01 to 1974-01-31; source msha-controller-operator-history
- **operator_operates_mine:** Hummel Properties Joint Venture → Boyers Coal Tipple; 1974-02-01 to 1974-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Hummel Properties Joint Venture → Boyers Coal Tipple; 1974-02-01 to 1974-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Hummel Properties Joint Venture → Hummel Properties Joint Venture; 1974-02-01 to 1974-12-31; source msha-controller-operator-history
- **operator_operates_mine:** C & K Coal Company → Boyers Coal Tipple; 1975-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gulf Usa Corp → C & K Coal Company; 1975-01-01 to current/open; source msha-controller-operator-history