# Relationship history for MSHA mine 3502780

Current hierarchy: **MDU Resources Group Inc → Beaver State Sand & Gravel-Div/LTM Inc → BEAVER 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

- **operator_operates_mine:** Beaver State Sand & Gravel → BEAVER PORTABLE; 1950-01-01 to 2000-08-28; source msha-controller-operator-history
- **controller_controls_mine:** John  Loosley → BEAVER PORTABLE; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  Loosley → Beaver State Sand & Gravel; 1950-01-01 to 2000-08-28; source msha-controller-operator-history
- **operator_operates_mine:** Beaver State Sand & Gravel-Div/LTM Inc → BEAVER PORTABLE; 2000-08-29 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → BEAVER PORTABLE; 2000-08-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Beaver State Sand & Gravel-Div/LTM Inc; 2000-08-29 to current/open; source msha-controller-operator-history