# Relationship history for MSHA mine 4200021

Current hierarchy: **CRH PLC → Staker & Parson Companies → Keigley 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:** United States Steel Corp → Keigley Quarry; 1950-01-01 to 1987-08-31; source msha-controller-operator-history
- **controller_controls_mine:** USX Corp (United States Steel Corp) → Keigley Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USX Corp (United States Steel Corp) → United States Steel Corp; 1950-01-01 to 1987-08-31; source msha-controller-operator-history
- **controller_controls_mine:** U S Aggregate Inc → Keigley Quarry; 1986-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Geneva Steel → Keigley Quarry; 1987-09-01 to 1999-10-14; source msha-controller-operator-history
- **controller_controls_mine:** Joseph A  Cannon → Keigley Quarry; 1987-09-01 to 1999-10-14; source msha-controller-operator-history
- **controller_controls_operator:** Joseph A  Cannon → Geneva Steel; 1987-09-01 to 1999-10-14; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Keigley Quarry; 1995-07-26 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Staker Paving & Construction Company Inc → Keigley Quarry; 1999-10-15 to 2001-03-31; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Staker Paving & Construction Company Inc; 1999-10-15 to 2001-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Western Aggregates → Keigley Quarry; 2001-04-01 to 2002-05-29; source msha-controller-operator-history
- **controller_controls_operator:** U S Aggregate Inc → Western Aggregates; 2001-04-01 to 2002-05-29; source msha-controller-operator-history
- **operator_operates_mine:** Staker & Parson Companies → Keigley Quarry; 2002-05-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** CRH PLC → Keigley Quarry; 2002-05-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** CRH PLC → Staker & Parson Companies; 2002-05-30 to current/open; source msha-controller-operator-history