Fallen Flag Railroads That Merged With Union Pacific:
- Chicago & North Western Transportation Company
- Denver & Rio Grande Western
- Missouri-Kansas-Texas
- Missouri Pacific
- Southern Pacific
- St. Louis Southwestern (Cotton Belt)
- Western Pacific
Fallen Flag Railroads That Merged With BNSF:
- Great Northern
- Northern Pacific
- Spokane, Portland & Seattle
- Chicago, Burlington & Quincy
- Colorado & Southern
- St. Louis-San Francisco (Frisco)
- Burlington Northern
- Atchison, Topeka & Santa Fe
Fallen Flag Railroads That Merged With Norfolk Southern:
- Erie Railroad
- Illinois Terminal Railroad Company
- Delaware, Lackawanna & Western
- Central Railroad of New Jersey (Jersey Central)
- New York Central
- Penn Central Transportation Company
- Reading Railroad Company
- Savannah & Atlanta
- Virginian Railway
- Wabash Railroad
- New York, New Haven & Hartford (New Haven)
- Central of Georgia
- Conrail
- Interstate Railroad
- Lehigh Valley
- Monongahela Railway
- New York, Chicago & St. Louis (Nickel Plate Road)
- Pennsylvania Railroad
- Norfolk & Western
- Southern Railway
- Norfolk Southern (Original)
Fallen Flag Railroads That Merged With CSX Transportation:
- Chesapeake & Ohio
- Baltimore & Ohio
- Western Maryland
- Seaboard Coast Line
- Louisville & Nashville
- Clinchfield Railroad
- Georgia Railroad & Banking Company
- Atlanta & West Point
- Western Railway of Alabama
- Chessie System
- Seaboard System