# Relationship history for MSHA mine 1900506

Current hierarchy: **Terry L  Edwards → T.L Edwards, Inc. → Plymouth Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Mayflower Sand & Gravel Company Inc → Plymouth Plant; 1950-01-01 to 1985-05-14; source msha-controller-operator-history
- **controller_controls_mine:** Sylvester A  Ray → Plymouth Plant; 1950-01-01 to 1985-05-14; source msha-controller-operator-history
- **controller_controls_operator:** Sylvester A  Ray → Mayflower Sand & Gravel Company Inc; 1950-01-01 to 1985-05-14; source msha-controller-operator-history
- **controller_controls_mine:** Terry L  Edwards → Plymouth Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mayflower Sand & Gravel → Plymouth Plant; 1985-05-15 to 2010-07-05; source msha-controller-operator-history
- **controller_controls_mine:** Louise  Landers et al → Plymouth Plant; 1985-05-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Louise  Landers et al → Mayflower Sand & Gravel; 1985-05-15 to 2010-07-05; source msha-controller-operator-history
- **operator_operates_mine:** T.L Edwards, Inc. → Plymouth Plant; 2010-07-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Terry L  Edwards → T.L Edwards, Inc.; 2010-07-06 to current/open; source msha-controller-operator-history