# Relationship history for MSHA mine 3000926

Current hierarchy: **Graymont Ltd → Malone Quarry → Porter Road**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Malone Concrete Products Company Inc → Porter Road; 1950-01-01 to 1979-08-27; source msha-controller-operator-history
- **controller_controls_mine:** Perrigo Charles V → Porter Road; 1950-01-01 to 1979-08-27; source msha-controller-operator-history
- **controller_controls_operator:** Perrigo Charles V → Malone Concrete Products Company Inc; 1950-01-01 to 1979-08-27; source msha-controller-operator-history
- **operator_operates_mine:** Malone Concrete Products Corp → Porter Road; 1979-08-28 to 1986-04-14; source msha-controller-operator-history
- **controller_controls_mine:** Bicknell Brothers Inc & St Lawrence Transit → Porter Road; 1979-08-28 to 1986-04-14; source msha-controller-operator-history
- **controller_controls_operator:** Bicknell Brothers Inc & St Lawrence Transit → Malone Concrete Products Corp; 1979-08-28 to 1986-04-14; source msha-controller-operator-history
- **controller_controls_mine:** Graymont Ltd → Porter Road; 1984-04-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Malone Quarry → Porter Road; 1986-04-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Graymont Ltd → Malone Quarry; 1986-04-15 to current/open; source msha-controller-operator-history