Census Areas Documentation

This Python library extends the Census API Wrapper to allow querying Census tracts, block groups, and blocks by Census place, as well as by arbitrary geographies.

Setup

Get the library and its dependencies using pip:

pip install census_area

Usage

from census_area import Census

c = Census("MY_API_KEY")
old_homes = c.acs5.state_place_tract(
   ('NAME', 'B25034_010E'), 17, 14000
)

The call above will return the name of the census tract and the number of homes that were built before 1939 for every tract in the City of Chicago. 17 is the FIPS code for Illinois and 14000 is the FIPS code for Chicago.

By default, this method will return a list of dictionaries, where each dictionary represents the data for one tract.

With the return_geometry argument, you can have the method return a geojson-like dictionary. Each tract is a feature, and the census variables about the tract appear in the feature’s property attributes.

old_homes_geojson = c.acs5.state_place_tract(
   ('NAME', 'B25034_010E'), 17, 14000,
   return_geometry=True
)

There are similar methods for block groups –

old_home_block_groups = c.acs5.state_place_blockgroup(
   ('NAME', 'B25034_010E'), 17, 14000
)

– and blocks.

owner_occupied = c.sf1.state_place_block(
   ('NAME', 'H016F0002'), 17, 14000
)

Note that block-level geographies are only available for the short-form data from the Decennial Census and redistricting summary files.

Summary of Available Geographic Resolutions

Series

Tract

Block Group

Block

ACS 5-Year Estimates

✅

✅

Decennial Census Short Form

✅

✅

✅

Redistricting Summary Files

✅

✅

✅

In addition to these convenient methods, there are lower level methods to get census tracts, blocks, and groups for arbitrary geometries: geo_tract(), geo_blockgroup(), geo_block().

Consider this example:

import json

with open('my_shape.geojson') as infile:
   my_shape_geojson = json.load(infile)

features = []

# N.b., your geometry must be in ESPG:4326
old_homes = c.acs5.geo_tract(
   ('NAME', 'B25034_010E'), my_shape_geojson['geometry']
)

for tract_geojson, tract_data, tract_proportion in old_homes:
   tract_geojson['properties'].update(tract_data)
   features.append(tract)

my_shape_with_new_data_geojson = {
   'type': 'FeatureCollection',
   'features': features
}

The geo_tract() method takes in the census variables you want and a geojson geometry, and returns a generator of the tract shapes, as geojson features, and the variables for that tract. Additionally, the generator returns a “tract proportion”; this is the proportion of the area of the tract that falls within your target shape.

geo_block() and geo_blockgroup() work in the same manner.

API

Census Object

class census_area.Census(key, year=None, session=None)

Unified API for accessing Census data

Attributes:

  • acs5: instance of ACS5Client

  • sf1: instance of SF1Client

  • pl: instance of PLClient

ACS5Client Object

class census_area.core.ACS5Client(key, year=None, session=None, retries=3)

Client to access American Community Survey 5-Year Estimates (see: https://www.census.gov/data/developers/data-sets/acs-5year.html)

state_place_tract(*args, **kwargs)

Retrieve variable values for tracts in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each tract containing variable values.

state_place_blockgroup(*args, **kwargs)

Retrieve variable values for block groups in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each block group containing variable values.

geo_tract(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for tracts intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each tract containing: tract geometry, dictionary containing variable values, and proportion of tract that overlaps with the arbitrary geometry

geo_blockgroup(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for block groups intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each block group containing: block group geometry, dictionary containing variable values, and proportion of block group that overlaps with the arbitrary geometry

SF1Client Object

class census_area.core.SF1Client(key, year=None, session=None, retries=3)

Client to access Census Summary File data (see https://www.census.gov/data/datasets/2010/dec/summary-file-1.html)

state_place_tract(*args, **kwargs)

Retrieve variable values for tracts in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each tract containing variable values.

state_place_blockgroup(*args, **kwargs)

Retrieve variable values for block groups in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each block group containing variable values.

state_place_block(*args, **kwargs)

Retrieve variable values for blocks in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each block containing variable values.

geo_tract(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for tracts intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each tract containing: tract geometry, dictionary containing variable values, and proportion of tract that overlaps with the arbitrary geometry

geo_blockgroup(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for block groups intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each block group containing: block group geometry, dictionary containing variable values, and proportion of block group that overlaps with the arbitrary geometry

geo_block(fields, geojson_geometry, year)

Retrieve variable values for blocks intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each block containing: block geometry, dictionary containing variable values, and proportion of block that overlaps with the arbitrary geometry

PLClient Object

class census_area.core.PLClient(key, year=None, session=None, retries=3)

Client to access Redistricting data (see https://www.census.gov/programs-surveys/decennial-census/about/rdo/summary-files.2020.html)

state_place_tract(*args, **kwargs)

Retrieve variable values for tracts in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each tract containing variable values.

state_place_blockgroup(*args, **kwargs)

Retrieve variable values for block groups in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each block group containing variable values.

state_place_block(*args, **kwargs)

Retrieve variable values for blocks in the specified state and incorporated place.

Arguments:

Returns:

List with dictionary for each block containing variable values.

geo_tract(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for tracts intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each tract containing: tract geometry, dictionary containing variable values, and proportion of tract that overlaps with the arbitrary geometry

geo_blockgroup(fields, geojson_geometry, year=None, **kwargs)

Retrieve variable values for block groups intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each block group containing: block group geometry, dictionary containing variable values, and proportion of block group that overlaps with the arbitrary geometry

geo_block(fields, geojson_geometry, year)

Retrieve variable values for blocks intersecting with an arbitrary geometry.

Arguments:

  • fields (iterable) - Variables to retrieve

  • geojson_geometry (dict) - Geometry object in ESPG:4326

  • year (int) - data year

Returns:

Generator with three-tuple for each block containing: block geometry, dictionary containing variable values, and proportion of block that overlaps with the arbitrary geometry