# Relationship history for MSHA mine 0202221

Current hierarchy: **Peter Kiewit Sons' Inc → United Metro Materials Inc → Portable #30-1082**

- 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:** Tanner Companies → Portable #30-1082; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Peter Kiewit Sons' Inc → Portable #30-1082; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Tanner Companies → Portable #30-1082; 1984-08-01 to 1987-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Tanner Companies → Tanner Companies; 1984-08-01 to 1987-08-31; source msha-controller-operator-history
- **operator_operates_mine:** Tanner Companies → Portable #30-1082; 1987-09-01 to 1994-07-12; source msha-controller-operator-history
- **controller_controls_mine:** Ashland Inc → Portable #30-1082; 1987-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ashland Inc → Tanner Companies; 1987-09-01 to 1994-07-12; source msha-controller-operator-history
- **operator_operates_mine:** United Metro Materials Inc → Portable #30-1082; 1994-07-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Peter Kiewit Sons' Inc → United Metro Materials Inc; 1994-07-13 to current/open; source msha-controller-operator-history