# Relationship history for MSHA mine 3901407

Current hierarchy: **Reinert Kenneth → Spearfish Excavating Inc → UNIT #1**

- 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:** Norman Gravel Sales Inc → UNIT #1; 1994-12-01 to 1996-04-23; source msha-controller-operator-history
- **controller_controls_mine:** Norman Billy H → UNIT #1; 1994-12-01 to 1996-04-23; source msha-controller-operator-history
- **controller_controls_operator:** Norman Billy H → Norman Gravel Sales Inc; 1994-12-01 to 1996-04-23; source msha-controller-operator-history
- **operator_operates_mine:** Spearfish Excavating Inc → UNIT #1; 1996-04-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Reinert Kenneth → UNIT #1; 1996-04-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Reinert Kenneth → Spearfish Excavating Inc; 1996-04-24 to current/open; source msha-controller-operator-history