# Relationship history for MSHA mine 4500975

Current hierarchy: **Granite Construction Inc → Granite Construction Company → Whatcom Portable Mill**

- 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

- **controller_controls_mine:** Granite Construction Inc → Whatcom Portable Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Wilder Construction Company → Whatcom Portable Mill; 1950-01-01 to 2008-04-03; source msha-controller-operator-history
- **controller_controls_mine:** Donald M  March et al → Whatcom Portable Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Donald M  March et al → Wilder Construction Company; 1950-01-01 to 2008-04-03; source msha-controller-operator-history
- **controller_controls_mine:** Granite Construction Inc → Whatcom Portable Mill; 2007-04-12 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Granite Northwest Inc → Whatcom Portable Mill; 2008-04-04 to 2009-04-05; source msha-controller-operator-history
- **controller_controls_operator:** Granite Construction Inc → Granite Northwest Inc; 2008-04-04 to 2009-04-05; source msha-controller-operator-history
- **operator_operates_mine:** Granite Construction Company → Whatcom Portable Mill; 2009-04-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Granite Construction Inc → Granite Construction Company; 2009-04-06 to current/open; source msha-controller-operator-history