Find the county for a city, state

Question

I have a city + state information and I'm trying to find the county. I tried a few things. The closest I got is using geopy. Here is an example:

from geopy.geocoders import Nominatim
geolocator = Nominatim()
loc = geolocator.geocode('Chicago Illinois')
print(loc.address)
# u'Chicago, Cook County, Illinois, United States of America'
loc = geolocator.geocode('San Francisco California')
print(loc.address) 
# u'SF, California, United States of America'

The problem is that it is unclear if the county is part of the output and if it is how to extract it using code (the string format seems to change).

What is the best way to get County information for a city + state?

Answer 1

That's one weakness as geopy does not guarantee county in its response. If you're open to other APIs, the U.S. Small Business Administration has an U.S. City & County Web Data API with an "All data for a specific City" endpoint, that has counties for cities that are ambiguously both cities and counties like City and County of San Francisco.

The API has xml or json response formats. The only change needed for your examples is using state abbreviations:

import requests
import json

locations = ['Chicago, IL', 'San Francisco, CA']

city_data_url = 'http://api.sba.gov/geodata/primary_links_for_city_of/%s/%s.json'

for l in locations:
    split_name = l.split(', ')
    response = requests.get(city_data_url % tuple(split_name))

    resp_json = json.loads(response.text)
    print resp_json[0]['full_county_name']

Output:

Cook County
San Francisco County