The CDC uses case and test positivity data to determine whether to describe an area as a hot spot. NPR's analysis included any county that was designated as a hot spot July 1-7.
— Emerging hot spot: Counties "that have a high likelihood for becoming a hot spot in the next 1-7 days"
— Hot spot: Counties "that have reached a threshold of disease activity considered as being of high burden."
— Sustained hot spot: Counties "that have had a high sustained case burden and are at potentially higher risk for experiencing health care resource limitations."