These data quantify population and housing by census block.
Census blocks vary in area.
Within urban areas, they can be as small as a city block. At the other extreme, blocks can be thousands of acres in areas that are largely unpopulated public lands. For example, the figure at right shows the 4,146 census blocks for Mendocino County. The blocks become quite small in cities like Ukiah, but are very large in the portions of the county that are largely rural and dominated by public landholdings. Housing units in the census data include traditional forms of housing and also teepees, caves, and other less conventional dwellings.