WASHINGTON, July 6 -- A 68-year-old man was trimming bushes in Bethel Township, Pennsylvania, on July 2 when the heat caught up with him. Temperatures had crossed 100 degrees. The Berks County coroner's office ruled it a heart attack brought on by heat exhaustion. His name has not been made public. He is the number underneath the record books: the one person whose death is not a data point on a chart but the reason the chart matters.

The record books took a hit of their own that week. Washington hit 102 degrees, breaking a mark of 101 that had stood since 1872. The federal government had already declared an energy emergency as the Eastern power grid strained toward a demand record. Philadelphia and New York pushed toward triple digits wi...