# Relationship history for MSHA mine 1800567

Current hierarchy: **Aggregate Management, Inc → Laurel Sand & Gravel Inc → Annapolis Junction Operation**

- 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:** Contee Sand & Gravel Company Inc → Annapolis Junction Operation; 1950-01-01 to 1981-09-27; source msha-controller-operator-history
- **controller_controls_mine:** Contee Resources Inc → Annapolis Junction Operation; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Contee Resources Inc → Contee Sand & Gravel Company Inc; 1950-01-01 to 1981-09-27; source msha-controller-operator-history
- **operator_operates_mine:** Annapolis Junction Inc → Annapolis Junction Operation; 1981-09-28 to 1983-04-06; source msha-controller-operator-history
- **controller_controls_mine:** Ecroyd Richard J & Hugh W Levey → Annapolis Junction Operation; 1981-09-28 to 1983-04-06; source msha-controller-operator-history
- **controller_controls_operator:** Ecroyd Richard J & Hugh W Levey → Annapolis Junction Inc; 1981-09-28 to 1983-04-06; source msha-controller-operator-history
- **operator_operates_mine:** Laurel Sand & Gravel Inc → Annapolis Junction Operation; 1983-04-07 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Aggregate Management, Inc → Annapolis Junction Operation; 1983-04-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Aggregate Management, Inc → Laurel Sand & Gravel Inc; 1983-04-07 to current/open; source msha-controller-operator-history