# Relationship history for MSHA mine 1100168

Current hierarchy: **Porter John → Porter Brothers Inc → PORTER BROS. SWANSON ROAD 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:** Porter Brothers Inc → PORTER BROS. SWANSON ROAD QUARRY; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Porter John Et Al → PORTER BROS. SWANSON ROAD QUARRY; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Porter John Et Al → Porter Brothers Inc; 1950-01-01 to current/open; source msha-controller-operator-history