Thousands of Americans die annually from heat, a cause of death that is underreported. Human-driven climate change is intensifying summer heat, but the official tally of heat-related deaths in the United States does not capture the full extent of the issue. The data collection process is inconsistent and often incomplete, resulting in a significant undercount of heat-related deaths.

NPR partnered with Boston University to create a more comprehensive national count of deaths influenced by heat. The investigation took two years to complete and involved building a statistical model.

Further details on the investigation and its findings are available from the source.