How many ISPs are there in the United States?
Thousands of ISPs exist in the United States, ranging in size from “mom and pop” providers of dial-up service for a few dozen customers each to providers who offer services in all parts of the world and have hundreds of thousands or millions of dial-up and thousands of directly connected customers. ISPs are not confined to delivering service over telephone wires and now include cable TV companies and satellite operators. The smallest ISPs purchase Internet connectivity from larger ISPs. The somewhat larger ISPs purchase connectivity from still larger ISPs, frequently from more than one to establish redundant connections for reliability. The largest ISPs generally peer with each other. But peering is not limited to the largest ISPs. ISPs of all sizes peer with each other. Sources: http://www.nap.edu/html/digital_dilemma/appC.
