# Relationship history for MSHA mine 4502184

Current hierarchy: **Dave  Brown → Whatcom-Skagit Quarry → WHATCOM AND SKAGIT QUARRY**

- 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:** Whatcom-Skagit Quarries → WHATCOM AND SKAGIT QUARRY; 1950-01-01 to 1982-12-05; source msha-controller-operator-history
- **controller_controls_mine:** Howard  Hammer et al → WHATCOM AND SKAGIT QUARRY; 1950-01-01 to 1982-12-05; source msha-controller-operator-history
- **controller_controls_operator:** Howard  Hammer et al → Whatcom-Skagit Quarries; 1950-01-01 to 1982-12-05; source msha-controller-operator-history
- **operator_operates_mine:** Whatcom-Skagit Quarry → WHATCOM AND SKAGIT QUARRY; 1982-12-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dave  Brown → WHATCOM AND SKAGIT QUARRY; 1982-12-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dave  Brown → Whatcom-Skagit Quarry; 1982-12-06 to current/open; source msha-controller-operator-history