By the Numbers: Warming Up America; January 2003; Scientific American Magazine; by Rodger Doyle; 1 Page(s)

Central heating, available in the U.S. since the early 19th century, became popular only after the Civil War. Typically, coal-burning furnaces fueled the early systems. The furnaces warped and cracked, causing gases to escape, and had to be stoked frequently. It took years and countless small improvements, but by the mid-1920s the systems had become reliable and, with the emergence of oil-fired furnaces, more convenient.

Natural gas, which became widely available with the building of a pipeline infrastructure after World War II, had developed into the leading fuel by 1960. Its acceptance resulted in part from its versatility-unlike oil, it can power appliances such as clothes washers and dryers, ovens, ranges and outdoor grills. Because it comes primarily from U.S. and Canadian fields, natural gas is also less vulnerable than oil is to war and embargo. Oil remains the predominant fuel in a few areas, such as New England, where naturalgas pipelines have not yet thoroughly penetrated. Oil users in many regions have the advantage of being able to lock in the price of a season's supply and, in contrast to most gas users, can easily change their supplier.