# Relationship history for MSHA mine 1400102

Current hierarchy: **Martin Marietta Materials Inc → Martin Marietta Aggregates → Portable #872**

- 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:** Martin Marietta Materials Inc → Portable #872; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Sunflower Crushed Stone Inc → Portable #872; 1950-01-01 to 1986-12-21; source msha-controller-operator-history
- **controller_controls_mine:** David S  Walker → Portable #872; 1950-01-01 to 1986-12-21; source msha-controller-operator-history
- **controller_controls_operator:** David S  Walker → Sunflower Crushed Stone Inc; 1950-01-01 to 1986-12-21; source msha-controller-operator-history
- **controller_controls_mine:** Mid America Materials Company → Portable #872; 1986-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hallett Materials → Portable #872; 1986-12-22 to 1990-01-14; source msha-controller-operator-history
- **controller_controls_operator:** Mid America Materials Company → Hallett Materials; 1986-12-22 to 1990-01-14; source msha-controller-operator-history
- **operator_operates_mine:** Martin Marietta Aggregates → Portable #872; 1990-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martin Marietta Materials Inc → Martin Marietta Aggregates; 1990-01-15 to current/open; source msha-controller-operator-history