# Relationship history for MSHA mine 3901446

Current hierarchy: **Carolyn  Nissen; Doug  Nissen → Nissen Gravel → NISSEN GRAVEL**

- 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:** Nissen Gravel → NISSEN GRAVEL; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Doug  Nissen et al → NISSEN GRAVEL; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Doug  Nissen et al → Nissen Gravel; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Carolyn  Nissen et al → Nissen Gravel; 2000-07-01 to current/open; source msha-controller-operator-history