CPD - (Census Designated Places)
- Census counterpart of an incorporated place - separate from cities and towns
- Unincorporated places are given boundaries; no size threshold
- boundaries change every census
Tract:
- Developed in 1910 – began in cities at the urging of the Federation of Churches
- Always follow county boundary but only sometimes follow municipal boundaries
- Tract has about 4,000 people living within it – if it doubles in population size it will be split in half
- labeled with the initial tract number, for example 03 and .nn will be added like 03.01, etc.. this allows you to see the changes that have happened in that area over time
Block Group
- 600 to 3,000 population
- 240 to 1,200 housing units
Census Block
- Blocks are not defined by population
- smallest geographic level at which data are ever released (Decennial Census, not the ACS)
ZTCA (Zip Code Tabulation Area):
- Census does not produce population data at Zip Code level but to ZTCA’s
- Simulation of a zip code – given boundary areas (ZTCA’s) will have more of one zip code than another (example 700 of 87505 and 200 of 87507 in given boundary area)
NOTE: There are some people living in one community but receiving mail in another zip code because there are no mail services in their area so ZIP CODE information is not as useful as the ZTCA when looking at populations of given areas.