# Relationship history for MSHA mine 1600239

Current hierarchy: **United States Government → U S Department Of Energy → Weeks Island Storage Complex**

- 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:** Morton Salt Division → Weeks Island Storage Complex; 1950-01-01 to 1978-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Morton International Inc → Weeks Island Storage Complex; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Morton International Inc → Morton Salt Division; 1950-01-01 to 1978-06-30; source msha-controller-operator-history
- **controller_controls_mine:** United States Government → Weeks Island Storage Complex; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** U S Department Of Energy → Weeks Island Storage Complex; 1978-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** United States Government → U S Department Of Energy; 1978-07-01 to current/open; source msha-controller-operator-history