# Relationship history for MSHA mine 1102374

Current hierarchy: **Prairie Group → Prairie Material Sales, Inc. - Aggregate Division → Yard 93 - Elgin**

- 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:** Road Materials Corp → Yard 93 - Elgin; 1950-01-01 to 1994-07-18; source msha-controller-operator-history
- **controller_controls_mine:** E M Melahn Construction Company Inc → Yard 93 - Elgin; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** E M Melahn Construction Company Inc → Road Materials Corp; 1950-01-01 to 1994-07-18; source msha-controller-operator-history
- **controller_controls_mine:** Prairie Group → Yard 93 - Elgin; 1984-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Prairie Material N S A → Yard 93 - Elgin; 1994-07-19 to 2001-11-27; source msha-controller-operator-history
- **controller_controls_mine:** Prairie Group → Yard 93 - Elgin; 1994-07-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Prairie Group → Prairie Material N S A; 1994-07-19 to 2001-11-27; source msha-controller-operator-history
- **operator_operates_mine:** Prairie Material Sales, Inc. - Aggregate Division → Yard 93 - Elgin; 2001-11-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Prairie Group → Prairie Material Sales, Inc. - Aggregate Division; 2001-11-28 to current/open; source msha-controller-operator-history