# Relationship history for MSHA mine 1001936

Current hierarchy: **AECOM → URS Washington Division → Rasmussen Ranch**

- 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

- **controller_controls_mine:** Washington Group International Inc → Rasmussen Ranch; 1986-04-01 to 2007-11-14; source msha-controller-operator-history
- **operator_operates_mine:** URS Washington Division → Rasmussen Ranch; 1998-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Washington Group International Inc → URS Washington Division; 1998-02-01 to 2007-11-14; source msha-controller-operator-history
- **controller_controls_mine:** URS Corporation → Rasmussen Ranch; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_operator:** URS Corporation → URS Washington Division; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_mine:** AECOM → Rasmussen Ranch; 2015-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** AECOM → URS Washington Division; 2015-01-01 to current/open; source msha-controller-operator-history