# Relationship history for MSHA mine 1901211

Current hierarchy: **Northern Construction Holdings Inc → Northern Construction  Service LLC → Florida 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:** Northern Construction  Service LLC → Florida Pit; 2011-10-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John N  Rahkonen et al → Florida Pit; 2011-10-13 to 2025-04-28; source msha-controller-operator-history
- **controller_controls_operator:** John N  Rahkonen et al → Northern Construction  Service LLC; 2011-10-13 to 2025-04-28; source msha-controller-operator-history
- **controller_controls_operator:** John L  DiVito et al → Northern Construction  Service LLC; 2011-10-13 to 2025-04-28; source msha-controller-operator-history
- **controller_controls_mine:** Northern Construction Holdings Inc → Florida Pit; 2025-04-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Northern Construction Holdings Inc → Northern Construction  Service LLC; 2025-04-29 to current/open; source msha-controller-operator-history