Geocoding: Overview

Gaining proficiency in GIS can take considerable study and instruction, so this online tutorial is limited in scope. It covers how to geocode a table of addresses into points and generate descriptive statistics about the areas around those points. To understand basic operations such as adding data and creating maps, please see the tutorial Introduction to ArcGIS 10.

Geocoding takes a table of addresses and converts them to actual locations with latitude and longitude. With the geocoding capability of ArcGIS 10, a powerful geographic information system (GIS), you can turn a list of addresses into spatial data for mapping or combining with other data. The output is in the form of points in the shapefile format.

ArcGIS is not the only program for geocoding--Google Fusion Tables are an easier option--but the software does give you more control over the geocoding process and a better understanding of its accuracy.

ArcGIS needs two kinds of files in order to geocode:

1. A table of addresses. This can be in Excel, CSV, DBF, or TXT files. They can be full street addresses or more general areas, such as ZIP codes. If you are using an Excel file (XLS or XLSX), there are some tips and tricks you can follow to avoid problems.
   
   The address data must be in a specific format depending on the kind of address. For street addresses, the table must have separate columns for number and street, city, state, and ZIP.
   
   
2. An address locator. This is the information that ArcGIS uses to assign a location to an address. For geocoding full street addresses, the address locator will contain street segments with ranges of addresses on the right and left side of the street. For geocoding ZIP codes, the address locator will simply be a map of ZIP code areas.