# Relationship history for MSHA mine 2900090

Current hierarchy: **Gifford-Hill & Company Inc → Amcord Inc → Amcord Inc**

- 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:** Sundance Coal Company → Amcord Inc; 1950-01-01 to 1975-11-30; source msha-controller-operator-history
- **controller_controls_mine:** G N C Energy Corp → Amcord Inc; 1950-01-01 to 1975-11-30; source msha-controller-operator-history
- **controller_controls_operator:** G N C Energy Corp → Sundance Coal Company; 1950-01-01 to 1975-11-30; source msha-controller-operator-history
- **operator_operates_mine:** Amcoal Inc → Amcord Inc; 1975-12-01 to 1979-12-06; source msha-controller-operator-history
- **controller_controls_mine:** Amcord Inc → Amcord Inc; 1975-12-01 to 1979-12-06; source msha-controller-operator-history
- **controller_controls_operator:** Amcord Inc → Amcoal Inc; 1975-12-01 to 1979-12-06; source msha-controller-operator-history
- **operator_operates_mine:** Amcord Inc → Amcord Inc; 1979-12-07 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gifford-Hill & Company Inc → Amcord Inc; 1979-12-07 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gifford-Hill & Company Inc → Amcord Inc; 1979-12-07 to current/open; source msha-controller-operator-history