. "Modern US rail history" . . "railroad industries" . "American railroads" . "national railway system" . "Transport of goods by rail" . "America's passenger-train service" . . "U.S. railroads" . "United States National Railroad Network" . "railroading in the United States" . "United States railroad industry" . "railroad links" . "rail networks" . "period of railroad expansion" . "rail industry" . "Railroads" . "Rail transportation in the United States" . "trains" . "railways" . . "railroads" . . "rail traffic" . "United States" . "U.S. passenger rail service" . "United States railroading" . "rail" . "Rail transportation in the United States" . "rail transportation in the United States" . "Rail_transportation_in_the_United_States#Freight_railroads" . "North American rail network" . "rail service" . "railroad network" . "American railway" . "major expansion of railroad shipping" . "railroad" . . . . "railroads throughout the United States" . "rail transport" . . "North American rail system" . . . . "intercity passenger railroad service in the United States" . "American railways" . "railroad industry" . "passenger railroads" . . "American railroad" . "U.S. railroad industry" . "railroading" .