# Relationship history for MSHA mine 1600928

Current hierarchy: **Robert Q  Humble → Century Ready Mix Corp → Line Road Pit**

- 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:** Century Ready Mix Corp → Line Road Pit; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robert Q  Humble  et al → Line Road Pit; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robert Q  Humble  et al → Century Ready Mix Corp; 1978-03-09 to current/open; source msha-controller-operator-history