# Relationship history for MSHA mine 2400478

Current hierarchy: **Knife River Corporation → Knife River Billings → Billings Pit**

- 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:** Midland Materials Company → Billings Pit; 1950-01-01 to 1987-07-05; source msha-controller-operator-history
- **controller_controls_mine:** United Companies → Billings Pit; 1950-01-01 to 1987-07-05; source msha-controller-operator-history
- **controller_controls_operator:** United Companies → Midland Materials Company; 1950-01-01 to 1987-07-05; source msha-controller-operator-history
- **controller_controls_mine:** Dean  Studer → Billings Pit; 1987-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Midland O'Leary Inc → Billings Pit; 1987-07-06 to 1989-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Dean  Studer → Midland O'Leary Inc; 1987-07-06 to 1989-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Midland O'Leary Inc → Billings Pit; 1989-04-01 to 1990-06-30; source msha-controller-operator-history
- **controller_controls_mine:** United Companies → Billings Pit; 1989-04-01 to 1990-06-30; source msha-controller-operator-history
- **controller_controls_operator:** United Companies → Midland O'Leary Inc; 1989-04-01 to 1990-06-30; source msha-controller-operator-history
- **operator_operates_mine:** Midland O'Leary Inc → Billings Pit; 1990-07-01 to 1991-06-30; source msha-controller-operator-history
- **controller_controls_mine:** JTL Group Inc → Billings Pit; 1990-07-01 to 1991-06-30; source msha-controller-operator-history
- **controller_controls_operator:** JTL Group Inc → Midland O'Leary Inc; 1990-07-01 to 1991-06-30; source msha-controller-operator-history
- **controller_controls_mine:** JTL Group Inc → Billings Pit; 1990-07-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Midland O'Leary Inc → Billings Pit; 1991-07-01 to 1994-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Ralph J  Studer Jr → Billings Pit; 1991-07-01 to 1994-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Ralph J  Studer Jr → Midland O'Leary Inc; 1991-07-01 to 1994-12-31; source msha-controller-operator-history
- **operator_operates_mine:** Jtl Group Inc → Billings Pit; 1995-01-01 to 2002-06-23; source msha-controller-operator-history
- **controller_controls_operator:** JTL Group Inc → Jtl Group Inc; 1995-01-01 to 2002-06-23; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Billings Pit; 1999-09-01 to 2023-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Knife River Billings → Billings Pit; 2002-06-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Billings; 2002-06-24 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Billings Pit; 2023-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Knife River Billings; 2023-06-01 to current/open; source msha-controller-operator-history