# Relationship history for MSHA mine 4201438

Current hierarchy: **Lammert Tom → Lammert Mining → Bicentennial**

- 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:** Whitelock Corp → Bicentennial; 1950-01-01 to 1979-01-15; source msha-controller-operator-history
- **controller_controls_mine:** Whitelock Corp → Bicentennial; 1950-01-01 to 1979-11-30; source msha-controller-operator-history
- **controller_controls_operator:** Whitelock Corp → Whitelock Corp; 1950-01-01 to 1979-01-15; source msha-controller-operator-history
- **controller_controls_mine:** Commonwealth Edison Company → Bicentennial; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Cotter Corp → Bicentennial; 1979-01-16 to 1986-11-25; source msha-controller-operator-history
- **controller_controls_operator:** Commonwealth Edison Company → Cotter Corp; 1979-01-16 to 1986-11-25; source msha-controller-operator-history
- **controller_controls_mine:** Lammert Tom Et Al → Bicentennial; 1979-11-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Western States Resources → Bicentennial; 1986-11-26 to 1987-10-31; source msha-controller-operator-history
- **controller_controls_mine:** Mike D  Shumway et al → Bicentennial; 1986-11-26 to 1987-10-31; source msha-controller-operator-history
- **controller_controls_operator:** Mike D  Shumway et al → Western States Resources; 1986-11-26 to 1987-10-31; source msha-controller-operator-history
- **operator_operates_mine:** Lammert Mining → Bicentennial; 1987-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lammert Tom Et Al → Lammert Mining; 1987-11-01 to current/open; source msha-controller-operator-history