Nik Freeman maps America’s empty space:
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.
Canada is more dramatic.