# Relationship history for MSHA mine 0502818

Current hierarchy: **Siegrist Construction Company → Siegrist Construction Company → 6001 Pecos**

- 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:** Colowyo Improvement Company → 6001 Pecos; 1950-01-01 to 1978-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Northwestern Engineering Company → 6001 Pecos; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Northwestern Engineering Company → Colowyo Improvement Company; 1950-01-01 to 1978-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Siegrist Construction Company → 6001 Pecos; 1978-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Siegrist Construction Company Et Al → 6001 Pecos; 1978-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Siegrist Construction Company Et Al → Siegrist Construction Company; 1978-07-01 to current/open; source msha-controller-operator-history