# Relationship history for MSHA mine 2501074

Current hierarchy: **Ivel (Steve)  Bygland; Raelynn  Bygland → Bygland Sand & Gravel → Bygland Sand & 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Hoffmeister Frank → Bygland Sand & Gravel; 1981-06-03 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Loup Gravel Company → Bygland Sand & Gravel; 1987-03-01 to 2000-06-30; source msha-controller-operator-history
- **controller_controls_operator:** Hoffmeister Frank → Loup Gravel Company; 1987-03-01 to 2000-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Bygland Sand & Gravel → Bygland Sand & Gravel; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ivel (Steve)  Bygland  et al → Bygland Sand & Gravel; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ivel (Steve)  Bygland  et al → Bygland Sand & Gravel; 2000-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Raelynn  Bygland  et al → Bygland Sand & Gravel; 2000-07-01 to current/open; source msha-controller-operator-history