On July 12, 1995, a dangerous hot-air mass settled over Chicago, producing three consecutive days of temperatures over 99 degrees Fahrenheit, heat indices (which measure the heat experienced by a typical person) around 120, high humidity, and little evening cooling. The heat wave was not the most extreme weather system in the city's history, but it proved to be Chicago's most deadly environmental event. During the week of the most severe weather, 485 city residents, many of whom were old, alone, and impoverished, died of causes that medical examiners attributed to the heat. Several hundred decedents were never autopsied, though, and after the event the Chicago Department of Public Health discovered that 739 Chicagoans in excess of the norm had perished while thousands more had been hospitalized for heat-related problems.

The patterns of heat wave mortality show that the disaster had a social as well as an ecological etiology. Over 70 percent of the victims were aged 65 and above; and African American mortality rates were roughly 1.5 times higher than those for whites. The heat wave deaths were concentrated in the predominantly African American community areas on the South and West Sides of Chicago, the places that also have high mortality rates and low life expectancy during normal times. The extreme weather helped to make visible some of the new dangers related to aging, isolation, and concentrated poverty in Chicago.

Eric Klinenberg