# Relationship history for MSHA mine 2002992

Current hierarchy: **William E  Montgomery → Montgomery Aggregate Products Company → 544 CRUSHER**

- 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:** Stony Ridge Inc → 544 CRUSHER; 1996-11-01 to 2001-04-03; source msha-controller-operator-history
- **controller_controls_mine:** George  Piippo → 544 CRUSHER; 1996-11-01 to 2001-04-03; source msha-controller-operator-history
- **controller_controls_operator:** George  Piippo → Stony Ridge Inc; 1996-11-01 to 2001-04-03; source msha-controller-operator-history
- **controller_controls_mine:** William E  Montgomery → 544 CRUSHER; 1999-06-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Montgomery Aggregate Products Company → 544 CRUSHER; 2001-04-04 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William E  Montgomery → Montgomery Aggregate Products Company; 2001-04-04 to current/open; source msha-controller-operator-history