# Relationship history for MSHA mine 1508258

Current hierarchy: **Smith Willard → Smith Coal Company → No 1 Mine**

- 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:** Tom Williamson Coal Company → No 1 Mine; 1975-01-01 to 1975-04-21; source msha-controller-operator-history
- **controller_controls_mine:** Williamson Tom Coal Company → No 1 Mine; 1975-01-01 to 1975-04-21; source msha-controller-operator-history
- **controller_controls_operator:** Williamson Tom Coal Company → Tom Williamson Coal Company; 1975-01-01 to 1975-04-21; source msha-controller-operator-history
- **operator_operates_mine:** Mc Creary Coal Company → No 1 Mine; 1975-04-22 to 1977-02-14; source msha-controller-operator-history
- **controller_controls_mine:** Mc Creary Tom & Gilbert Smith → No 1 Mine; 1975-04-22 to 1977-02-14; source msha-controller-operator-history
- **controller_controls_operator:** Mc Creary Tom & Gilbert Smith → Mc Creary Coal Company; 1975-04-22 to 1977-02-14; source msha-controller-operator-history
- **operator_operates_mine:** Smith Coal Company → No 1 Mine; 1977-02-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Smith Willard → No 1 Mine; 1977-02-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Smith Willard → Smith Coal Company; 1977-02-15 to current/open; source msha-controller-operator-history