1. United Parcel Service), consolidated freight shipping, dramatic expansion of the automobile industry, and the growth of new communities alongside interstate highways. Incremental investments in the U.S. highway infrastructure at its current level of maturity are unlikely to engender these network effects. Such investments will not, for example, spur individuals to go out and purchase a new set of tires or faster cars. Hence, investments in the highway or other physical infrastructure in the United States are capable of delivering only the traditional employment multiplier. For more discussion, see Theofanis P. Mamuneas and M. Ishaq Nadiri;Consider that the net social rate of return on highway capital was very high, about 35 percent, when the U.S. interstate 4. highway system was first constructed in the 1950s and 1960s,1996
2. Discussion Series Working Paper No;D Stephen;Finance and Economics,2007