# Relationship history for MSHA mine 3501563

Current hierarchy: **Grant I  Sharp → Grant I Sharp Construction → Portable Plant #1**

- 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:** Hill Lloyd M Inc → Portable Plant #1; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** U S Forest Service → Portable Plant #1; 1950-01-01 to 1979-10-17; source msha-controller-operator-history
- **controller_controls_mine:** United States Government → Portable Plant #1; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** United States Government → U S Forest Service; 1950-01-01 to 1979-10-17; source msha-controller-operator-history
- **operator_operates_mine:** Lloyd M Hill Inc → Portable Plant #1; 1979-10-18 to 1987-03-30; source msha-controller-operator-history
- **controller_controls_operator:** Hill Lloyd M Inc → Lloyd M Hill Inc; 1979-10-18 to 1987-03-30; source msha-controller-operator-history
- **operator_operates_mine:** Grant I Sharp Construction → Portable Plant #1; 1987-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Grant I  Sharp → Portable Plant #1; 1987-03-31 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grant I  Sharp → Grant I Sharp Construction; 1987-03-31 to current/open; source msha-controller-operator-history