We use Google’s geo-coder to translate an address into a latitude and longitude set of coordinates to be placed on the map.

Sometimes an address is not found and other times it can be placed where it should not be. The geo-coder appears to work very well in most industrialized countries such as the United States. If a location cannot be mapped, sometimes modifying the address slightly will get the address to work. If you only have a zip (or postal) code adding a country will improve the accuracy if it gets placed in the wrong country.

You can manually type in an address to see where Google’s geo-coder will place an address .

Be aware that google’s geo-coder is not the same as typing something in on Google Maps. Google maps most likely uses google’s vast search capabilities to find out where a restaurant, store, address, and other places should be placed on the map.

The accuracy of the geo-coding can be viewed in the EasyMapMaker Accuracy column in the data (emm_acc). The following 4 values can occur:

  • ROOFTOP

    indicates that the returned result is a precise geocode for which we have location information accurate down to street address precision.

  • RANGE_INTERPOLATED

    indicates that the returned result reflects an approximation (usually on a road) interpolated between two precise points (such as intersections). Interpolated results are generally returned when rooftop geocodes are unavailable for a street address.

  • GEOMETRIC_CENTER

    indicates that the returned result is the geometric center of a result such as a polyline (for example, a street) or polygon (region).

  • APPROXIMATE

    indicates that the returned result is approximate.

If an address does not have results, the address will be placed in the error table.