# Relationship history for MSHA mine 0503741

Current hierarchy: **Grand County-Co → Grand County Road & Bridge Department → Kremmling Airport**

- 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:** Grand County-Co → Kremmling Airport; 1980-12-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Grand County Road & Bridge Department → Kremmling Airport; 1981-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grand County-Co → Grand County Road & Bridge Department; 1981-09-01 to current/open; source msha-controller-operator-history