I'm used to maps showing some sort of data by state and county (though there is one memorable one that uses a dot per person). We're now getting maps with data by census block. The US Census Bureau started using blocks in 1990 to improve their population count. Some are about the size of a city block, those in the vacant west might be a couple hundred square miles. Across the 50 states and Puerto Rico there are over 11 million census blocks.
Nik Freeman noted a lot of maps show where the American population is, so he made one where the population is not. To do that he colored each census block that has a population of zero. That's 4.8 million census blocks or 47% of America. Of course, a large chunk of that is in Alaska.
Though I haven't seen a description it seems that the entire country is divided into census blocks -- even where there are obviously no residents, such as highways, industrial parks, and rivers. While we expect highlighted areas for the mountainous and desert spaces in the West as well as for national parks, the map also shows us highlighted rivers. I wonder if large Plains farms are divided into multiple census blocks. The block with the farmhouse would show as inhabited but the cultivated fields would show zero residents, even though the land is owned and in use.
There are vacant areas in the northern part of Michigan's Lower Peninsula and more in the Upper Peninsula. A large vacant area that might be a surprise to some is northern Maine. I'll check some of that this summer, though I won't be going through the largest area of no inhabitants.