# Relationship history for MSHA mine 1901004

Current hierarchy: **Kenneth  Heffron → Heffron Asphalt Corp → HEFFRON MTLS-WOBURN**

- 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:** Kenneth  Heffron → HEFFRON MTLS-WOBURN; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Site Development Inc → HEFFRON MTLS-WOBURN; 1986-03-01 to 1990-09-20; source msha-controller-operator-history
- **controller_controls_mine:** Curran Albert Jr → HEFFRON MTLS-WOBURN; 1986-03-01 to 1990-09-20; source msha-controller-operator-history
- **controller_controls_operator:** Curran Albert Jr → Site Development Inc; 1986-03-01 to 1990-09-20; source msha-controller-operator-history
- **operator_operates_mine:** Heffron Asphalt Corp → HEFFRON MTLS-WOBURN; 1990-09-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kenneth  Heffron → Heffron Asphalt Corp; 1990-09-21 to current/open; source msha-controller-operator-history