# Relationship history for MSHA mine 0504587

Current hierarchy: **Marilyn L  Curry → Tri County Gravel → Hotchkiss Plant**

- 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:** Tri County Gravel → Hotchkiss Plant; 1997-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Marilyn L  Curry et al → Hotchkiss Plant; 1997-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Marilyn L  Curry et al → Tri County Gravel; 1997-03-01 to current/open; source msha-controller-operator-history