# Relationship history for MSHA mine 1900020

Current hierarchy: **Amrize Ltd → Amrize Northeast Inc. → Amrize Swampscott Quarry**

- 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:** Lynn Sand & Stone Company → Amrize Swampscott Quarry; 1950-01-01 to 1983-08-30; source msha-controller-operator-history
- **controller_controls_mine:** James H  Cooke → Amrize Swampscott Quarry; 1950-01-01 to 1983-08-30; source msha-controller-operator-history
- **controller_controls_operator:** James H  Cooke → Lynn Sand & Stone Company; 1950-01-01 to 1983-08-30; source msha-controller-operator-history
- **operator_operates_mine:** Lynn Sand & Stone Company → Amrize Swampscott Quarry; 1983-08-31 to 1988-05-03; source msha-controller-operator-history
- **controller_controls_mine:** Guyott Company → Amrize Swampscott Quarry; 1983-08-31 to 1988-05-03; source msha-controller-operator-history
- **controller_controls_operator:** Guyott Company → Lynn Sand & Stone Company; 1983-08-31 to 1988-05-03; source msha-controller-operator-history
- **operator_operates_mine:** Amrize Northeast Inc. → Amrize Swampscott Quarry; 1988-05-04 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Aggregate Industries PLC → Amrize Swampscott Quarry; 2001-06-01 to 2009-04-29; source msha-controller-operator-history
- **controller_controls_operator:** Aggregate Industries PLC → Amrize Northeast Inc.; 2001-06-01 to 2009-04-29; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Amrize Swampscott Quarry; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Amrize Northeast Inc.; 2009-04-30 to 2015-07-09; source msha-controller-operator-history
- **controller_controls_mine:** Holcim Ltd → Amrize Swampscott Quarry; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_operator:** Holcim Ltd → Amrize Northeast Inc.; 2015-07-10 to 2025-06-22; source msha-controller-operator-history
- **controller_controls_mine:** Amrize Ltd → Amrize Swampscott Quarry; 2025-06-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Amrize Ltd → Amrize Northeast Inc.; 2025-06-23 to current/open; source msha-controller-operator-history