# Relationship history for MSHA mine 2103187

Current hierarchy: **Blair B  Bury → Midwest Asphalt Corporation → MAC #4**

- 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:** Blaine M  Johnson → MAC #4; 1995-06-01 to 2010-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Midwest Asphalt Corporation → MAC #4; 1998-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blaine M  Johnson → Midwest Asphalt Corporation; 1998-11-01 to 2010-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Blair B  Bury → MAC #4; 2010-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blair B  Bury → Midwest Asphalt Corporation; 2010-05-01 to current/open; source msha-controller-operator-history