Introduction to geocoding

We'll first take a look at an example of geocoding, to give you a better feel for the process. If you have an address located at 150 Main St., you must first geocode the address to determine its geographic coordinates.

If 150 Main St lies on a street segment with an address range of 100 to 200 Main St., the geocoding process interpolates the location of 150 Main St. to be exactly halfway along this street segment. It then assigns 150 Main St. to the geographic location that corresponds to the point halfway between 100 and 200 Main St. This process is described in the following figure.

Now that you have the coordinates for the address, you can then plot it on the map:

This is the most common way in which street addresses are geocoded. It works best in urban areas where addresses tend to be regularly spaced. However, it is less reliable in areas where addresses are not regularly spaced and for addresses in cul-de-sacs. It is notoriously unreliable in very rural locations...