# Relationship history for MSHA mine 3304204

Current hierarchy: **Jerome  Osborne → Twinsburg Development Corp → Twinsburg Development Corp.**

- 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:** Aurora Sand & Gravel Company → Twinsburg Development Corp.; 1990-06-01 to 1997-04-13; source msha-controller-operator-history
- **controller_controls_mine:** Gary  Helf → Twinsburg Development Corp.; 1990-06-01 to 1997-04-13; source msha-controller-operator-history
- **controller_controls_operator:** Gary  Helf → Aurora Sand & Gravel Company; 1990-06-01 to 1997-04-13; source msha-controller-operator-history
- **operator_operates_mine:** Twinsburg Development Corp → Twinsburg Development Corp.; 1997-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Jerome  Osborne et al → Twinsburg Development Corp.; 1997-04-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jerome  Osborne et al → Twinsburg Development Corp; 1997-04-14 to current/open; source msha-controller-operator-history