On Thursday, July 13, 1995, Chicagoans awoke to a blistering day in which the temperature would reach 106 degrees. The heat index, which measures how the temperature actually feels on the body, would hit 126 degrees by the time the day was over. Meteorologists had been warning residents about a two-day heat wave, but these temperatures did not end that soon. When the heat wave broke a week later, city streets had buckled; the records for electrical use were shattered; and power grids had failed, leaving residents without electricity for up to two days. And by July 20, over seven hundred...