Description from the US Census Bureau (see link for source):Standard block groups are clusters of blocks within the same census tract that have the same first digit of their 4-character census block number. For example, blocks 3001, 3002, 3003..., 3999 in census tract 1210.02 belong to Block Group 3. Due to boundary and feature changes that occur throughout the decade, current block groups do not always maintain these same block number to block group relationships. For example, block 3001 might move due to a census tract boundary change but the block number will not change, even if it does not still fall in block group 3. However, the GEOID for that block, identifying block group 3, would remain the same in the attribute information in the TIGER/Line Shapefiles because block GEOIDs are always built using the decennial geographic codes.
block_groups(state = NULL, county = NULL, cb = FALSE, year = NULL, ...)The two-digit FIPS code (string) of the state you want. Can also
be state name or state abbreviation. When NULL and combined with
cb = TRUE, a national dataset of block groups will be returned for
years 2019 and later.
The three-digit FIPS code (string) of the county you'd like to subset for, or a vector of FIPS codes if you desire multiple counties. Can also be a county name or vector of names.
If cb is set to TRUE, download a generalized (1:500k) file. Defaults to FALSE (the most detailed TIGER/Line file)
the data year; defaults to 2022
arguments to be passed to internal function load_tiger, which is not exported. See Additional Arguments.
Additional arguments that can be passed in ... are:
class Desired class of return object: "sf" (the default) or "sp". sp classes should be considered deprecated as of tigris version 2.0, but legacy support is still available.
progress_bar If set to FALSE, do not display download progress bar (helpful for R Markdown documents). Defaults to TRUE.
keep_zipped_shapefile If set to TRUE, do not delete zipped shapefile (stored in temporary directory or TIGRIS_CACHE_DIR
depending on the configuration of global option "tigris_use_cache"). Defaults to FALSE.
refresh Whether to re-download cached shapefiles (TRUE or FALSE) . The default is either FALSE or the value of global
option "tigris_refresh" if it is set. Specifying this argument will override the behavior set in "tigris_refresh" global option.
filter_by Geometry used to filter the output returned by the function. Can be an sf object, an object of class bbox, or a length-4 vector of format c(xmin, ymin, xmax, ymax) that can be converted to a bbox. Geometries that intersect the input to filter_by will be returned.
Block groups delineated for the 2010 Census generally contain between 600 and 3,000 people. Most block groups were delineated by local participants in the Census Bureau's Participant Statistical Areas Program (PSAP). The Census Bureau delineated block groups only where a local or tribal government declined to participate or where the Census Bureau could not identify a potential local participant.
A block group usually covers a contiguous area. Each census tract contains at least one block group and block groups are uniquely numbered within census tract. Within the standard census geographic hierarchy, block groups never cross county or census tract boundaries, but may cross the boundaries of county subdivisions, places, urban areas, voting districts, congressional districts, and American Indian, Alaska Native, and Native Hawaiian areas.
https://www2.census.gov/geo/pdfs/maps-data/data/tiger/tgrshp2020/TGRSHP2020_TechDoc.pdf
Other general area functions:
blocks(),
counties(),
county_subdivisions(),
places(),
pumas(),
school_districts(),
states(),
tracts(),
zctas()
if (FALSE) {
library(tigris)
benton_bgs <- block_groups("Oregon", "Benton")
plot(benton_bgs$geometry)
}
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