Unrelenting heat wave bakes half the U.S.; 30 dead

Perspiration collects on construction worker David Macmullen's face in the afternoon heat, Friday, July 6, 2012, in Philadelphia. The National Weather Service said the record-breaking heat that has baked the nation’s midsection for several days was slowly moving into the mid-Atlantic states and Northeast. Excessive-heat warnings remained in place Friday for all of Iowa, Indiana and Illinois as well as much of Wisconsin, Michigan, Missouri, Ohio and Kentucky. (AP Photo/Matt Rourke)