A Block is the smallest area unit used by the U.S. Census Bureau for tabulating statistics. As of the 2010 census, the United States consists of 11,078,300 Census Blocks. Of them, 4,871,270 blocks totaling 4.61 million square kilometers were reported to have no population living inside them. Despite having a population of more than 310 million people, 47 percent of the USA remains unoccupied.
Green shading indicates unoccupied Census Blocks. A single inhabitant is enough to omit a block from shading.Not all of the green area is wilderness, though.
The map tends to highlight two types of areas: places where human habitation is physically restrictive or impossible, and places where human habitation is prohibited by social or legal convention.
Water features such lakes, rivers, swamps and floodplains are revealed as places where it is hard for people to live. In addition, the mountains and deserts of the West, with their hostility to human survival, remain largely void of permanent population.
Of the places where settlement is prohibited, the most apparent are wilderness protection and recreational areas (such as national and state parks) and military bases. At the national and regional scales, these places appear as large green tracts surrounded by otherwise populated countryside.
At the local level, city and county parks emerge in contrast to their developed urban and suburban surroundings. At this scale, even major roads such as highways and interstates stretch like ribbons across the landscape.
Commercial and industrial areas are also likely to be green on this map. The local shopping mall, an office park, a warehouse district or a factory may have their own Census Blocks. But if people don’t live there, they will be considered “uninhabited”. So it should be noted that just because a block is unoccupied, that does not mean it is undeveloped.But, generally, it’s easier to find solitude in the western half of the country. Right now I'm in one of those green areas at the bottom edge of California.