Although "Blue Zone" might sound like something political (e.g., "Urban areas in the United States tend to be Blue Zones"), it's not. A Blue Zone is one of the places in the world (e.g., Okinawa Prefecture, Japan; Nuoro Province, Sardinia, Italy; Icaria, Greece) where residents are known for being disproportionately likely to live long lives. They are called blue zones because the researchers who first studied them used blue pens to mark up their maps.