# Relationship history for MSHA mine 4201963

Current hierarchy: **Summit Materials LLC → LeGrand Johnson → Portable Crusher Unit B**

- 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:** Janice  Sackett et al → Portable Crusher Unit B; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harold  Elam → Portable Crusher Unit B; 1950-01-01 to 2011-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Le Grand Johnson Construction Company → Portable Crusher Unit B; 1985-10-01 to 2015-08-21; source msha-controller-operator-history
- **controller_controls_operator:** Janice  Sackett et al → Le Grand Johnson Construction Company; 1985-10-01 to 2015-08-21; source msha-controller-operator-history
- **controller_controls_operator:** Larry  Jardine et al → Le Grand Johnson Construction Company; 1985-10-01 to 2015-08-21; source msha-controller-operator-history
- **controller_controls_mine:** Summit Materials LLC → Portable Crusher Unit B; 2011-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** LeGrand Johnson → Portable Crusher Unit B; 2015-08-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harold  Elam → LeGrand Johnson; 2015-08-22 to 2011-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Summit Materials LLC → LeGrand Johnson; 2015-08-22 to current/open; source msha-controller-operator-history