# Relationship history for MSHA mine 1001940

Current hierarchy: **AECOM → Washington Group International Inc → Wells Cargo Mine**

- 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

- **controller_controls_mine:** Washington Group International Inc → Wells Cargo Mine; 1986-04-01 to 2007-11-14; source msha-controller-operator-history
- **operator_operates_mine:** Washington Group International Inc → Wells Cargo Mine; 1998-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Washington Group International Inc → Washington Group International Inc; 1998-05-01 to 2007-11-14; source msha-controller-operator-history
- **controller_controls_mine:** URS Corporation → Wells Cargo Mine; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_operator:** URS Corporation → Washington Group International Inc; 2007-11-15 to 2014-12-31; source msha-controller-operator-history
- **controller_controls_mine:** AECOM → Wells Cargo Mine; 2015-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** AECOM → Washington Group International Inc; 2015-01-01 to current/open; source msha-controller-operator-history