geolocation - Google Maps: how to get country, state/province/region, city given a lat/long value?

Question

I need a list of countries, states & cities based on a collection of lat/long values I have. I need to store this information in a manner that hierarchy is preserve and without duplicates (e.g. "USA" and "United States" and "United States of America" are the same country; I only want one instance of this country in my database).

Is this possible to do with Google Map API?

Answer 1

What you are looking for is called reverse geocoding. Google provides a server-side reverse geocoding service through the Google Geocoding API, which you should be able to use for your project.

This is how a response to the following request would look like:

http://maps.googleapis.com/maps/api/geocode/json?latlng=40.714224,-73.961452&sensor=false

Response:

{
  "status": "OK",
  "results": [ {
    "types": [ "street_address" ],
    "formatted_address": "275-291 Bedford Ave, Brooklyn, NY 11211, USA",
    "address_components": [ {
      "long_name": "275-291",
      "short_name": "275-291",
      "types": [ "street_number" ]
    }, {
      "long_name": "Bedford Ave",
      "short_name": "Bedford Ave",
      "types": [ "route" ]
    }, {
      "long_name": "New York",
      "short_name": "New York",
      "types": [ "locality", "political" ]
    }, {
      "long_name": "Brooklyn",
      "short_name": "Brooklyn",
      "types": [ "administrative_area_level_3", "political" ]
    }, {
      "long_name": "Kings",
      "short_name": "Kings",
      "types": [ "administrative_area_level_2", "political" ]
    }, {
      "long_name": "New York",
      "short_name": "NY",
      "types": [ "administrative_area_level_1", "political" ]
    }, {
      "long_name": "United States",
      "short_name": "US",
      "types": [ "country", "political" ]
    }, {
      "long_name": "11211",
      "short_name": "11211",
      "types": [ "postal_code" ]
    } ],
    "geometry": {
      "location": {
        "lat": 40.7142298,
        "lng": -73.9614669
      },
      "location_type": "RANGE_INTERPOLATED",
      "viewport": {
        "southwest": {
          "lat": 40.7110822,
          "lng": -73.9646145
        },
        "northeast": {
          "lat": 40.7173774,
          "lng": -73.9583193
        }
      }
    }
  },

  ... Additional results[] ...

You can also opt to receive the response in xml instead of json, by simply substituting json for xml in the request URI:

http://maps.googleapis.com/maps/api/geocode/xml?latlng=40.714224,-73.961452&sensor=false

As far as I know, Google will also return the same name for address components, especially for high-level names like country names and city names. Nevertheless, keep in mind that while the results are very accurate for most applications, you could still find the occasional spelling mistake or ambiguous result.