# Relationship history for MSHA mine 2400475

Current hierarchy: **Steve R  Campbell → Mastodon Sand & Gravel Inc → Mastodon Sand & Gravel Inc**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Mastodon Sand & Gravel → Mastodon Sand & Gravel Inc; 1950-01-01 to 1995-12-21; source msha-controller-operator-history
- **controller_controls_mine:** Steve R  Campbell → Mastodon Sand & Gravel Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steve R  Campbell → Mastodon Sand & Gravel; 1950-01-01 to 1995-12-21; source msha-controller-operator-history
- **operator_operates_mine:** Mastodon Sand & Gravel Inc → Mastodon Sand & Gravel Inc; 1995-12-22 to 2001-11-06; source msha-controller-operator-history
- **controller_controls_mine:** Barbara  Campbell → Mastodon Sand & Gravel Inc; 1995-12-22 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Barbara  Campbell → Mastodon Sand & Gravel Inc; 1995-12-22 to 2001-11-06; source msha-controller-operator-history
- **operator_operates_mine:** Mastodon Sand & Gravel Inc → Mastodon Sand & Gravel Inc; 2001-11-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Steve R  Campbell → Mastodon Sand & Gravel Inc; 2001-11-07 to current/open; source msha-controller-operator-history