Slide 26 of 29
Notes:
This diagram of the Census geographic hierarchy presents this information as a series of nesting relationships. For example, a line joining the lower-level entity place and the higher-level entity state means that a place cannot cross a state boundary; a line linking census tract and county means that a census tract cannot cross a county line; and so forth. The areas on the outside of the main middle line do not necessarily follow along and have census tracts or block groups. As you can see, they do all relate back to the most basic unit, the census block.
More data are available for the larger geographic areas, such as the states and counties. Less data are available for smaller geographic units such as census tracts and blocks.
