census_shapes

A Ruby Gem that facilitates the importing US Census Shapefiles into a PostGIS database.

Prerequisites

This gem requires Postgres / PostGIS and is intended to be used with a Rails 3 application.

Installation

To install the 'census_shapes' ruby gem:

gem install census_shapes

To use the gem in your Rails 3 Application, include the gem in your Gemfile:

gem "census_shapes"

SETUP

1) $ rails generate census_shapes:setup

To setup your rails application to use census_shapes, run the following generator:

rails g census_shapes:setup MODEL_NAME

This will create all the necessary files, including:

config/database_example.yml
db/###_create_geographies.rb
lib/tasks/postgis_template.rake
lib/tasks/census_shapes.rake

app/models/geography.rb
app/controllers/geographies_controller.rb
app/views/layouts/geographies.html.erb
app/assets/stylesheets/geographies.css.scss
app/views/geographies/partials/_map.erb

2) Setup your Database

The generator will create an example database configuration file at: config/database_example.yml.

Edit the database, template, username and password values for your environment. Change the postgis_path for the appropriate environment(s). If you installed PostGIS through homebrew on OS X, the development path should be: /usr/local/share/postgis/

Rename the file database.yml.

3) Create a PostGIS Template

In your application directory, run the following rake task from the command console:

rake postgis_template:create

The generator uses the values set in database.yml, including the postgis_path to find the necessary PostGIS SQL files, and will generate a template database if one does not already exist.

3) Migrate Database

If Postgres / PostGIS is setup properly and the database.yml and template database are configured, you should now be able to migrate the database:

rake db:migrate

4) Import Census Geographies

With the database migrated, we may import the census geographies:

rake census_shapes:import SHAPE=DESIRED_SHAPES

Replace DESIRED_SHAPES with the slugs of the Census Shapes you wish to import. For example, to import States and Counties, you would run the following command:

rake census_shapes:import SHAPE=STATE,COUNTY

The import process will download the zips of the required Census Shapes to 'tmp/shapefiles', unless a path is specified with the PATH argument:

rake census_shapes:import SHAPE=STATE,COUNTY PATH=/usr/local/shapefiles

Lastly, the Zip files will be deleted after import unless the ARCHIVE argument is specified:

rake census_shapes:import SHAPE=STATE,COUNTY ARCHIVE=true

For a full list of the 22 supported Census Geographic Summary Levels, see 'Summary Levels' of the 'Usage' section.

Note: Depending upon your internet speed and the amount of Census Shapes you require, this may take several hours or days to complete.

5) Validate Geometry (Optional)

Depending upon the Census Shapes you install, validation may be required. For example:

rake census_shapes:validate_geometry SHAPE=STATE,COUNTY

The validate_geometry rake task will test and repair the geometries of all imported shapes.

USAGE

Summary Levels

Census-Geographies will import the following 22 Geographic Summary Levels:

Sumlevel - Slug: Name

040 - STATE: State
050 - COUNTY: County
060 - COUSUB: County Subdivision
067 - SUBMCD: Subminor Civil Subdivision
101 - BLOCK: Block
140 - TRACT: Tract
150 - BG: Blockgroup
160 - PLACE: Place
230 - ANRC: Alaska Native Regional Corporation
280 - AIANNH: American Indian Area/Alaska Native Area/Hawaiian Home Land
281 - AITS: American Indian Tribal Subdivision
320 - CBSA: Metropolitan Statistical Area/Micropolitan Statistical Area
323 - METDIV: Metropolitan Division
340 - CSA: Combined Statistical Area
500 - CD: Congressional District (111th)
610 - SLDU: State Legislative District (Upper Chamber)
620 - SLDL: State Legislative District (Lower Chamber)
700 - VTD: Voting District
871 - ZCTA5: ZIP Code Tabulation Area (5-Digit)
950 - ELSD: School District (Elementary)
960 - SCSD: School District (Secondary)
970 - UNSD: School District (Unified)