Here is a map of standardized mortality ratios at the county level:
More information from Reuters:
"According to our results, the answer is heat," Susan Cutter and Kevin Borden of the University of South Carolina wrote in their report, which gathered data from 1970 to 2004.
"I think what most people would think, if you say what is the major cause of death and destruction, they would say hurricanes and earthquakes and flooding," Cutter said in a telephone interview. "They wouldn't say heat."
"What is noteworthy here is that over time, highly destructive, highly publicized, often-catastrophic singular events such as hurricanes and earthquakes are responsible for relatively few deaths when compared to the more frequent, less catastrophic such as heat waves and severe weather," they wrote.
The most dangerous places to live are much of the South, because of the heat risk, the hurricane coasts and the Great Plains states with their severe weather, Cutter said.
The south central United States is also a dangerous area, with floods and tornadoes.
California is relatively safe, they found.