timelets

In 1940, 55 percent of all the residences in the country were heated with coal or coke (77 percent of the central heating systems); by 1950, just five years after the end of hostilities, that figure had dropped to 35 percent, and by 1970 to 2 percent of the total (US Bureau of the Census, 1940, 1950, 1970). If one can rely on the accuracy of the consumer price indexes, the price of coal remained roughly on a par with the price of electricity, gas, and fuel oil during this period. What, then, can explain the flight from coal?

-- Ruth Schwartz Cowan. The Consumption Junction: A Proposal for Research Strategies in the Sociology of Technology. ibid.