Relating Block Groups to ZIP Code Areas
April 2019. The popularity of block group demographic data is mainly due to this being the smallest geographic area for which annually updated demographic data, with U.S. wall-to-wall coverage, are available from the American Community Survey (ACS) -- or any other source. While block groups nest within census tracts from both a geometric and geocode hierarchy perspective, the relationship between block groups and ZIP code areas is far less clear. Analysts are often interested in relating block group geography and demographics with ZIP code areas. The Census 2010 217,740 block groups intersect with 32,824 ZIP code areas forming 308,805 BG-ZIP area combinations. This section provides tools to examine the relationship between block group geography/demographics and ZIP code areas.
Block Group 06-075-015700-1 in Context of ZIP Code Area 94115
Block groups (BGs) are often wholly contained within a ZIP code area. But around the ZIP code area boundary, intersecting block groups are often split by the ZIP code boundary. This relationship is illustrated in the graphic shown below. This graphic shows block group 06-075-015700-1 (yellow BG code label, cross-hatched, black boundary) in context of ZIP Code area 94115 (white labels, bold blue boundary) located in San Francisco. This GIS application is closely related to the Mapping Block Group Data, also uses the San Francisco area in applications.
- view developed with ProximityOne CV XE GIS and related GIS project.
- view all San Francisco ZIP code areas; see ZIP 94115 in context.
The cross-hatched BG 060750157001(or 06-075-015700-1) is split by ZIP code 94115. What part of the BG is in ZIP code area 94115 and adjacent ZIP code area 94118? The situation is similar for BG 060750157002, directly below 060750157001, which is split into 3 ZIP code areas. Use the interactive table to make these determinations.
Relating Block Groups and ZIP Code Areas Using the Interactive Table
The interactive table shown below contains a row for block group area part which intersects with a unique ZIP code area. The simple case of a BG being split into two ZIP code areas can be visually observed as shown in the graphic presented above. A tabular relational table offers processing advantages compared to visual geospatial depictions. Here is an example. ZIP code area 94115 contains whole or parts of 32 BGs. To view/verify this using the table below, 1) click the SHowAll button below the table, then 2) click the Find ZIP button (edit box at right preloaded with this ZIP). The table refreshes with 32 rows -- the BGs intersecting with this ZIP code area. Verify there are 32 BGs; the BG codes can be viewed in column 1.
In the map at the top of this section, block group 06-075-015700-1 is shown visually to be contained in two ZIP code areas. To view how block group 06-075-015700-1 is split among multiple ZIP code areas using the table below, 1) click the SHowAll button below the table, then 2) click the Find GEOID button (enter G060750157001 in the edit box to right of Find GEOID then click Find button). The table refreshes with two BGs. In this example, it can be seen that the total BG population (Census 2010) is 1,375. The part of the BG population is shown and the percent of the population from that BG allocated to the corresponding ZIP code are shown. This BG has a total area 0.09 square miles. The part of the BG area Census 2010, square miles) is shown and the percent of the area from that BG allocated to the corresponding ZIP code are shown. See more using the table in the usage notes section below the table.
Block Group to ZIP Code Area Relationship Interactive Table
Click column header to sort; click again to sort other direction. See more usage notes below table.
See related Ranking Tables Main Page
Click ShowAll button between specific queries.
Use Find GEOID> button to select/filter based on BG GEOID column.
- Click ShowAll button first.
- Enter search text in edit box to right of Find GEOID> button.
... Must start with "G" (no quotes).
... Gssccc filters for ss (state FIPS) and ccc (county FIPS).
... Gssccctttttt filters for ss (state FIPS) ccc (county FIPS) and tttttt (tract).
... Gsscccttttttb filters for ss (state FIPS) ccc (county FIPS) tttttt (tract) b (blockgroup).
- Default value G06075 will filter to all block groups in San Francisco County, CA (06075).
Use Seq> button to select only "first instance" of a ZIP code.
- Click ShowAll button first.
- Only use value 1 in this version.
- Enables identification of one BG in each BG; filters to one occurrence of all ZIP codes.
Click row (turns blue) select, then right-click to copy to clipboard.
Columns (all items as of Census 2010)
BG GEOID -- character G plus 12 character block group code
State -- USPS state
BG Population -- part of total BG population in ZIP
BG Population -- percent of total BG Population
BG Area -- part of total BG area (square miles) in ZIP
BG Area -- percent of total BG area (square miles) in ZIP,
ZIP Sequence -- 1 or 0; 1 used to select unique ZIP row set
ZIP Code Population
Determining Block Group & Block Group Demographics based on Address
Key in an address here to view demographic-economic characteristics (and associated geographic codes) for that location (.e.g., for corresponding block group, census tract or other area containing that address).
Support Using these Resources
Learn more about accessing and using demographic-economic data and related analytical tools. Join us in a Data Analytics Lab session. There is no fee for these one-hour Web sessions. Each informal session is focused on a specific topic. The open structure also provides for Q&A and discussion of application issues of interest to participants.
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