# Relationship history for MSHA mine 2900885

Current hierarchy: **GMS Inc; David  Shoup → United Materials, LLP → Carlsbad Airport Pit**

- 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

- **operator_operates_mine:** Armstrong Construction Company Inc → Carlsbad Airport Pit; 1950-01-01 to 2016-02-15; source msha-controller-operator-history
- **controller_controls_mine:** Bill B  Armstrong Jr  et al → Carlsbad Airport Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bill B  Armstrong Jr  et al → Armstrong Construction Company Inc; 1950-01-01 to 2016-02-15; source msha-controller-operator-history
- **controller_controls_mine:** GMS Inc et al → Carlsbad Airport Pit; 2015-05-08 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** United Materials, LLP → Carlsbad Airport Pit; 2016-02-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** GMS Inc et al → United Materials, LLP; 2016-02-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David  Shoup et al → United Materials, LLP; 2016-02-16 to current/open; source msha-controller-operator-history