# Relationship history for MSHA mine 1509961

Current hierarchy: **Johnson Frelland → Frelland Johnson Coal Company → No 2 Mine**

- 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 Frelland Et Al → No 2 Mine; 1974-09-06 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Oak Ridge Coal Company Inc → No 2 Mine; 1976-09-01 to 1977-03-07; source msha-controller-operator-history
- **controller_controls_mine:** Coleman Clifford & Ermal B Et Al → No 2 Mine; 1976-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Coleman Clifford & Ermal B Et Al → Oak Ridge Coal Company Inc; 1976-09-01 to 1977-03-07; source msha-controller-operator-history
- **operator_operates_mine:** Frelland Johnson Coal Company → No 2 Mine; 1977-03-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Johnson Frelland Et Al → Frelland Johnson Coal Company; 1977-03-08 to current/open; source msha-controller-operator-history