# Relationship history for MSHA mine 4502526

Current hierarchy: **Taiheiyo Cement Corp → CalPortland Company → Maury Island Sand & Grav dba CalPortland**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **controller_controls_mine:** Morrison Knudsen Corp (Old) → Maury Island Sand & Grav dba CalPortland; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Morrison-Knudsen Company Inc → Maury Island Sand & Grav dba CalPortland; 1978-03-09 to 1988-01-24; source msha-controller-operator-history
- **controller_controls_operator:** Morrison Knudsen Corp (Old) → Morrison-Knudsen Company Inc; 1978-03-09 to 1988-01-24; source msha-controller-operator-history
- **controller_controls_mine:** Taiheiyo Cement Corp → Maury Island Sand & Grav dba CalPortland; 1988-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kimm Company Inc → Maury Island Sand & Grav dba CalPortland; 1988-01-25 to 1999-07-13; source msha-controller-operator-history
- **controller_controls_mine:** Kimmel Mike → Maury Island Sand & Grav dba CalPortland; 1988-01-25 to 2002-05-15; source msha-controller-operator-history
- **controller_controls_operator:** Kimmel Mike → Kimm Company Inc; 1988-01-25 to 1999-07-13; source msha-controller-operator-history
- **controller_controls_mine:** Taiheiyo Cement Corp → Maury Island Sand & Grav dba CalPortland; 1990-10-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Northwest Aggregates → Maury Island Sand & Grav dba CalPortland; 1999-07-14 to 2001-06-21; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → Northwest Aggregates; 1999-07-14 to 2001-06-21; source msha-controller-operator-history
- **operator_operates_mine:** Kimmco Incorporated → Maury Island Sand & Grav dba CalPortland; 2001-06-22 to 2006-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Kimmel Mike → Kimmco Incorporated; 2001-06-22 to 2002-05-15; source msha-controller-operator-history
- **controller_controls_mine:** Taiheiyo Cement Corp → Maury Island Sand & Grav dba CalPortland; 2002-05-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → Kimm Company Inc; 2002-05-16 to 1999-07-13; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → Kimmco Incorporated; 2002-05-16 to 2006-03-31; source msha-controller-operator-history
- **operator_operates_mine:** CalPortland → Maury Island Sand & Grav dba CalPortland; 2006-04-01 to 2009-08-31; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → CalPortland; 2006-04-01 to 2009-08-31; source msha-controller-operator-history
- **operator_operates_mine:** CalPortland Company → Maury Island Sand & Grav dba CalPortland; 2009-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Taiheiyo Cement Corp → CalPortland Company; 2009-09-01 to current/open; source msha-controller-operator-history