Petroleum is the main source of energy for transportation.
oil
The bullet train
flying cars
Horses, wagons and trains
Petroleum.
Not really sure car probably.
petroleum
"Oil and gas" US dollars
Maksim Yuryevich Sokolov is the Minister of Transportation for Russia.
Kansas' main source of income comes from agricultural products, primarily cattle and wheat. Kansas also receives income from manufacturing items, the main manufactured product is transportation equipment.
The Amish