# Relationship history for MSHA mine 1301357

Current hierarchy: **Swales Earl R → Swales Concrete Inc → Essman Island Sand 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:** Roverud Construction Inc → Essman Island Sand Pit; 1950-01-01 to 1981-05-13; source msha-controller-operator-history
- **controller_controls_mine:** Jeff C Roverud et al → Essman Island Sand Pit; 1950-01-01 to 2004-02-04; source msha-controller-operator-history
- **controller_controls_operator:** Jeff C Roverud et al → Roverud Construction Inc; 1950-01-01 to 1981-05-13; source msha-controller-operator-history
- **controller_controls_operator:** Curtis G Roverud et al → Roverud Construction Inc; 1950-01-01 to 1981-05-13; source msha-controller-operator-history
- **operator_operates_mine:** Swales Concrete Inc → Essman Island Sand Pit; 1981-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Swales Earl R → Essman Island Sand Pit; 1981-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Swales Earl R → Swales Concrete Inc; 1981-05-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Essman Island Sand Pit; 2004-02-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Roverud Construction Inc; 2004-02-05 to 1981-05-13; source msha-controller-operator-history