# Relationship history for MSHA mine 1900949

Current hierarchy: **Leigh  Tryon → TRYON CONSTRUCTION → TRYON CONSTRUCTION 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:** R W Tryon Construction Company → TRYON CONSTRUCTION PIT; 1978-03-09 to 2018-04-15; source msha-controller-operator-history
- **controller_controls_mine:** R W Tryon Construction Company → TRYON CONSTRUCTION PIT; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** R W Tryon Construction Company → R W Tryon Construction Company; 1978-03-09 to 2018-04-15; source msha-controller-operator-history
- **operator_operates_mine:** Tryon Construction → TRYON CONSTRUCTION PIT; 2018-04-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Leigh  Tryon → TRYON CONSTRUCTION PIT; 2018-04-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leigh  Tryon → Tryon Construction; 2018-04-16 to current/open; source msha-controller-operator-history