When the US does its census, the smallest measurement unit it goes by is the “block.” In a city, this is what you would think it is: a city block. In the country, the size is more arbitrary. But there are a grand total of 11,078,300 census blocks in the United States…and 4,871,270 of them are totally uninhabited.
That’s what the map above (by the website mapsbynik) shows. Any blocks with even a single person living in them are shaded white, while those in green have no human residents.