# Relationship history for MSHA mine 2000729

Current hierarchy: **Dykema LP → Grand Rapids Gravel Company → PLANT #14-PLAINFIELD**

- 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:** Grand Rapids Gravel Company → PLANT #14-PLAINFIELD; 1950-01-01 to 1987-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Grand Rapids Gravel Company → PLANT #14-PLAINFIELD; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grand Rapids Gravel Company → Grand Rapids Gravel Company; 1950-01-01 to 1987-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Grand Rapids Gravel Company → PLANT #14-PLAINFIELD; 1987-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dykema LP → PLANT #14-PLAINFIELD; 1987-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dykema LP → Grand Rapids Gravel Company; 1987-07-01 to current/open; source msha-controller-operator-history