# Relationship history for MSHA mine 2501141

Current hierarchy: **Roland W  Johnson → Johnson Sand & Gravel Corp → Plant #2**

- 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

- **controller_controls_mine:** Roland W  Johnson → Plant #2; 1983-09-16 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Johnson Sand & Gravel Corp → Plant #2; 1992-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roland W  Johnson → Johnson Sand & Gravel Corp; 1992-06-01 to current/open; source msha-controller-operator-history