The development of recent decades most obviously likely to be continued is the tendency for alternative methods of traveling to coexist, and so to offer potential travelers a choice. Within large cities, underground transport is usually an alternative to several ways of traveling on the surface. Roads, railways and airlines are in competition, and there are still people who cross the North Atlantic by sea. (Most freight goes that way, of course.)

Oil tankers could decisively affect the pattern of petroleum distribution from the major oilfields and at the same time encourage the pipeline, which offers the simplest and often the cheapest means of bulk transport. Then, there is the Boeing 747 aircraft, which is likely to do for people what the huge tankers will do for petroleum trunk be increasingly troublesome. All these changes, promised or merely possible in the pattern of transport, have in common what is, in the broadest sense, and economic stimulus.

Fast transport between cities separated by a few hundred miles is becoming urgently necessary in densely populated areas. The United States Government is financing a number of exploratory investigations bearing on specific problems linking the major cities on the Atlantic seaboard. However, it remains to be seen whether the result will really beyond schemes for patching up the existing railway network to some of the more ambitious schemes which are sometimes heard of--monorails, pneumatic tubes with trains inside, and deep bored tunnels intended to enable trains to oscillate from one city to another with no expenditure of energy except for overcoming friction and air resistance. Several means of travel will be present together, in which each can replace the others.