US Counties

A GeoJSON object containing geometries of every county in the US.

Data courtesy of https://github.com/jgoodall/us-maps, which was derived from US Census shapefiles.

Installation

npm install us-counties

⚠️ This module loads a ~170MB JSON object into memory, so your mileage may vary. See server usage or consider running your process with the v8 max-old-space-size flag, like node -–max-old-space-size=8192 your-file.js.

Programmatic Usage

This module plays nicely with the which-polygon package for looking up counties by lng/lat coordinate:

const counties = require('us-counties')
const whichPolygon = require('which-polygon')
const findCounty = whichPolygon(counties)
const coords = [-109.82152075444654, 33.987415215464544]
const result = findCounty(coords)

Results look like this:

{ STATEFP10: '04',
  COUNTYFP10: '001',
  COUNTYNS10: '00025441',
  GEOID10: '04001',
  NAME10: 'Apache',
  NAMELSAD10: 'Apache County',
  LSAD10: '06',
  CLASSFP10: 'H1',
  MTFCC10: 'G4020',
  CSAFP10: null,
  CBSAFP10: null,
  METDIVFP10: null,
  FUNCSTAT10: 'A',
  ALAND10: 29001443825,
  AWATER10: 54175788,
  INTPTLAT10: '+35.3858453',
  INTPTLON10: '-109.4937467',
  state: 'AZ' }

Server Usage 🚀

If you're writing a program that is already hungry for RAM, you can avoid out-of-memory errors by running this module as a webserver in a separate process:

$ npx us-counties

Now there's a server running on port 5000. Make requests by passing lng and lat as query params, like localhost:5000/?lng=-109.82152075444654&lat=33.987415215464544

npm i -g json
curl -s "http://localhost:5000/?lng=-109.82152075444654&lat=33.987415215464544" | json

Fields

From https://www2.census.gov/geo/pdfs/maps-data/data/tiger/tgrshp2010/TGRSHP10SF1AA.pdf

License

MIT