# Relationship history for MSHA mine 2501121

Current hierarchy: **Johnson Calvin → Nebraska Credit Finance Corp → North 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

- **controller_controls_mine:** Johnson Calvin Et Al → North Pit; 1983-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Nebraska Credit Finance Corp → North Pit; 1990-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Johnson Calvin Et Al → Nebraska Credit Finance Corp; 1990-03-01 to current/open; source msha-controller-operator-history