# Relationship history for MSHA mine 3300067

Current hierarchy: **Heidelberg Materials AG → Heidelberg Materials Midwest Agg, Inc. → North Baltimore Shop**

- 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:** France Stone Company → North Baltimore Shop; 1950-01-01 to 1986-09-30; source msha-controller-operator-history
- **controller_controls_mine:** France Stone Company → North Baltimore Shop; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** France Stone Company → France Stone Company; 1950-01-01 to 1986-09-30; source msha-controller-operator-history
- **operator_operates_mine:** France Stone Company → North Baltimore Shop; 1986-10-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Company Inc → North Baltimore Shop; 1986-10-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → France Stone Company; 1986-10-01 to 1988-11-13; source msha-controller-operator-history
- **operator_operates_mine:** Heidelberg Materials Midwest Agg, Inc. → North Baltimore Shop; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → North Baltimore Shop; 1988-11-14 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Heidelberg Materials Midwest Agg, Inc.; 1988-11-14 to 2007-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Heidelberg Materials AG → North Baltimore Shop; 2007-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Heidelberg Materials AG → Heidelberg Materials Midwest Agg, Inc.; 2007-08-23 to current/open; source msha-controller-operator-history