So what is a GEO Locator anyway?

A Geo Locator takes the components of a Geo-Coder-a tool that converts an address, city, state and zip code to earth coordinates (longitude and latitude) and a locator, a tool that leverages geometry and spatial data to produce a resulting set of desired items and their distance in proximity to the Geo-Coded addresses.

A prime example of a geo locator can be found on http://www.culligan.com/, click the find/locate your dealer tab. That particular locator leverages Culligan's Knoweldge Base that was converted to a igital format then applied to mapping and geo-coding software. The result is a dealer locator that honnors specific "hand drawn" territories.

The benefits to this approach are many:

• Accuracy - By geocoding we pin point an exact location then match that to a precicely drawn map of the dealer's territory. In many cases the lines of two adjacent territories literally split streets in half, one side to one dealer one, one side to another dealer. As a result this level of precision is required. Zip codes, or even Zip+4 will not be accurate enough. Besides most people don't even know their Zip+4 so the effort is frutiless. Geo-Coding with predfined territories is the most accurate.
• Lower Maintenance - Maintenacne of a Geographic system is based on more slow changing things like established territories. Zip codes on the other hand are in a constant state of flux, as such their innards (the zip+4 areas) are also in a state of flux. This makes it very difficult to maintain locators, and makes you pay a penalty if you wish to do that at a higher accuracy level. Remember all those zip codes need to be correlated to all of your dealers, hense there is a lot more data than meets the eye, espeically if sharing zip codes is common.
• Most Flexible - Once you have digital areas representing your partnerships and their territories, you can correlate those dealers to services they provide, adding another dimension of accuracy, and improving your request to partner success rate.
• Scales Internationally- Top end Geo-Coding tools are written to plug in other countries address systems without having to modify code. This means one solution scales to the entire planet. You are limited only by your architecture.
• Organizational Mapping is key to mining your customer data - How are my partners performing in their territory? More importantly what are realistic goals for them? These questions can be answered once you have your dealer maps digitized. You can combine these partner territories with census track data to get a picture of the Micro-Economy of your dealer's territory.

Culligan.com has a locator that demonstrates this http://www.culligan.com/dealerindex.asp. I'm the original author and ongoing IT project manager for the locator server. That particular locator uses MapInfo "MapXTreme" as the geo-search and "MapMarker Plus" as the geo-coder to locate your Culligan Dealer. It is by and far the most accurate and complex locator I have come across (it's not perfect, but still more accurate than anything else).

Unfortunately there is a serious downside:

The cost to own this technology is prohibitive. It is licensed in such a way that it's not cost effecive to aggregate use of a license (several different companies running the same instance falls under a differnent and very costly license). The drawbacks are cost and expertice in maintenance. In short GIS systems are very costly. Usually $150,000+ to get started and ongoing costs can range from $50,000 to $150,000 per year. You might want to make sure you have a very product knowledgable staff member at arms length as well.

If you are really looking for a "Find Nearest" type of search that can have accuracy within a few miles, zip code may be the best way to go.

Less accurate but useful alternatives

Zip Locator

For all the negatives cited above, postal code locators are still a great way to get basic results. Accuracy is usually within ten miles in very rural areas (maybe twenty in the boonedocks).  It increases in areas where the population density is higher because zips fill up in less geographical area:

   high population density = smaller postalcode areas = shorter distance between postal centroids

So let's put this into a realistic perspective. For most of the population the results will be accurate within six miles. That's good enough to give you a choice of nearby locations. Top quality data for the US starts at around $600 per year with updates at zip+4 level it's much more, but I'm not aware of any databases that do that for cheap, just costly enough to put top quality geocoding (and who actually remembers their zip+4 anyway?).

Using basic technology it's possible to get reasonable results from a zip based locator See the retail locator in action.

Are you interested in locator technologies for your company Contact Us we have a great tool built into our SiteBuilder software and the price is right!

City/State Locator

Maybe all you need is to find exact matches by City. This works well if you use a geographical drill down map where in four or five clicks a person can select their city. Typing the city in a text box is perhaps the least valueable locator in general because there are all kinds of problems interpreting the way people type a city (St. Louis vs Saint Louis, st.lous, etc...) with zip all you need is five digits that everyone remembers. State is acceptable if you have a very small number of dealers per state, and the customer can choose any location to transact. Much easier to communicate those digits over the phone and much easier to type on the internet. In short I don't really recommend this type of search. However....

Hybrid of City/State and Zip

If you could combine a list of zip codes in a city and locate within that region, I hypothesize that is the best scenario for city and state. At this point my hypothesis is just that, it remains untested.