On the surface, the national numbers would indicate that homes were not much likelier to receive water from public systems in 1990 than 1970. For three censuses, public water systems served a bit over 80 percent of all homes. Yet, there were interesting variations in some parts of the Nation in that time period.

In 1990, some states in the South Region were more likely to have public water systems than they were 20 years earlier. North and South Carolina illustrate this trend well. Many highly urban States, such as Illinois, Utah, and California barely changed from 1970 to 1990. But, in some States, homes were less likely in 1990 to be served by public water systems than in 1970; New England States are typical of this group.