Because transporting often crosses regional, national, or international borders, governments play an important role by developing transportation systems. In the U.S., railroads carry more freight over more miles than any other mode. Railcar shipping is slow and limited to where track is laid but is ideal for many bulk and nonperishable goods. Trucks are more expensive than railroads as a shipping alternative but they offer tremendous flexibility for connecting buyers and sellers. In countries with good road systems, trucks are also a fast transportation alternative.
Water transportation is the slowest mode, but usually the lowest cost way to ship heavy freight.
Water transport is also the only feasible way to ship most internationally traded goods. Shipping by airplane is the most expensive transporting mode but also the fastest. Further, time-sensitive materials and business documents can well be worth the cost of quick delivery. This is something of a specialty mode, limited to goods like oil and natural gas. Combining modes can sometimes save costs.