# Relationship history for MSHA mine 4800837

Current hierarchy: **BHP Billiton → Rio Algom Mining Corp → SMITH RANCH PROJECT**

- 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:** Sequoyah Fuels Corp → SMITH RANCH PROJECT; 1950-01-01 to 1989-03-26; source msha-controller-operator-history
- **controller_controls_mine:** Kerr-McGee Corp → SMITH RANCH PROJECT; 1950-01-01 to 1989-03-26; source msha-controller-operator-history
- **controller_controls_operator:** Kerr-McGee Corp → Sequoyah Fuels Corp; 1950-01-01 to 1989-03-26; source msha-controller-operator-history
- **controller_controls_mine:** Rio Algom Ltd → SMITH RANCH PROJECT; 1978-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Rio Algom Mining Corp → SMITH RANCH PROJECT; 1989-03-27 to 2000-10-09; source msha-controller-operator-history
- **controller_controls_operator:** Rio Algom Ltd → Rio Algom Mining Corp; 1989-03-27 to 2000-10-09; source msha-controller-operator-history
- **operator_operates_mine:** Rio Algom Mining Corp → SMITH RANCH PROJECT; 2000-10-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** BHP Billiton → SMITH RANCH PROJECT; 2000-10-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** BHP Billiton → Rio Algom Mining Corp; 2000-10-10 to current/open; source msha-controller-operator-history