If price is the deciding factor, the car trip will usually be the cheaper one for anything more than a single passenger or a single passenger with infant child in tow. (Kids under two generally ride the train free.)
Autonomous vehicles (AVs) and AIAVs combined with artificial intelligence (AI) will provide a future of convenience and comfort when it comes to future transport. Banished to yesteryears will be bus timetables and shelters, and nose-to-bumper stress driving.
Air freight is safer, more reliable, and faster than ocean freight, but it's also about 5 times more expensive on average – meaning a $200 ocean shipment can cost $1,000 by air. Airlines also have stricter regulations when it comes to shipping hazardous materials.
The cheapest way to travel across America depends on the mode of transportation. Generally speaking, taking the bus or the train is the most cost effective way to cover a long distance. If you plan ahead, long-distance bus companies such as Greyhound and Megabus often offer discounted fares.