# Relationship history for MSHA mine 1901208

Current hierarchy: **Brian  Pierce; Harold L  Pierce Jr. → Pierce Builders Inc. → Portable Plant**

- 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:** Pierce Builders Inc. → Portable Plant; 2011-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harold L  Pierce Jr. et al → Portable Plant; 2011-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harold L  Pierce Jr. et al → Pierce Builders Inc.; 2011-04-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brian  Pierce et al → Pierce Builders Inc.; 2011-04-19 to current/open; source msha-controller-operator-history