# Relationship history for MSHA mine 2002800

Current hierarchy: **Robert  Land → Ottawa Aggregates, Inc. → A.C. Plant #1 Portable**

- 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:** Robert  Land → A.C. Plant #1 Portable; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Ottawa Aggregates, Inc. → A.C. Plant #1 Portable; 1988-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert  Land → Ottawa Aggregates, Inc.; 1988-04-01 to current/open; source msha-controller-operator-history