# Relationship history for MSHA mine 4102840

Current hierarchy: **North American Construction Group, LTD → NACG Texas, Inc. → San Miguel Lignite 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** NACCO Industries Inc → San Miguel Lignite Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** San Miguel Electric Cooperative Inc → San Miguel Lignite Mine; 1979-01-01 to 1980-07-13; source msha-controller-operator-history
- **controller_controls_mine:** Mac A  Coalson → San Miguel Lignite Mine; 1979-01-01 to 1980-07-13; source msha-controller-operator-history
- **controller_controls_operator:** Mac A  Coalson → San Miguel Electric Cooperative Inc; 1979-01-01 to 1980-07-13; source msha-controller-operator-history
- **operator_operates_mine:** Atascosa Mining Company → San Miguel Lignite Mine; 1980-07-14 to 1997-06-30; source msha-controller-operator-history
- **controller_controls_mine:** Washington Group International Inc → San Miguel Lignite Mine; 1980-07-14 to 1997-06-30; source msha-controller-operator-history
- **controller_controls_operator:** Washington Group International Inc → Atascosa Mining Company; 1980-07-14 to 1997-06-30; source msha-controller-operator-history
- **operator_operates_mine:** The North American Coal Corp → San Miguel Lignite Mine; 1997-07-01 to 2010-12-31; source msha-controller-operator-history
- **controller_controls_operator:** NACCO Industries Inc → The North American Coal Corp; 1997-07-01 to 2010-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Kiewit Peter Sons' Inc → San Miguel Lignite Mine; 2004-08-21 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Kiewit Mining Group, Inc. → San Miguel Lignite Mine; 2011-01-01 to 2020-06-20; source msha-controller-operator-history
- **controller_controls_operator:** Kiewit Peter Sons' Inc → Kiewit Mining Group, Inc.; 2011-01-01 to 2020-06-20; source msha-controller-operator-history
- **operator_operates_mine:** NACG Texas, Inc. → San Miguel Lignite Mine; 2020-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** North American Construction Group, LTD → San Miguel Lignite Mine; 2020-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** North American Construction Group, LTD → NACG Texas, Inc.; 2020-06-21 to current/open; source msha-controller-operator-history