# Relationship history for MSHA mine 3605723

Current hierarchy: **Brooks Howard G → Helm Mining Company → Eagle #12 Strip**

- 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:** Helm Mining Company → Eagle #12 Strip; 1975-09-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brooks Howard G Et Al → Eagle #12 Strip; 1975-09-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brooks Howard G Et Al → Helm Mining Company; 1975-09-08 to current/open; source msha-controller-operator-history