A Google Groups thread has discussion on the topic of dynamically creating pages to target localized searches. For example, this particular webmaster wants to be able to target 28 different zip codes for his client's A/C business. He summarizes what he wants to do:
Johns A/C does work in 28 different zip codes. He creates 28 webspages, page names reflect the township AC_service_City_zip.htm, meta tags reflect city, zip such as Johns AC serivce serving the "City" and "zip code" area. Then the body is a template and the city and zip are filled in for each city/zip area.
This way when someone does a search for AC service "zipcode" or "city" there is a good chance his page will be included.
This was a popular SEO tactic years and years ago. These days, it is much harder to rank well for terms using the automated city database methodology. We actually covered some of the databases you can purchase to accomplish this back in 2005. But is this legit?
According to Google, no it is not. In fact, Googler, Reid, said that the manner in which this webmaster wants to go, seems to be a "doorway page." Reid said:
I agree with webado in this scenario. If the body of these pages is a template and the only thing that changes is the city and zip code, this sounds a lot like doorway pages:
Why push the limit on how much duplicate content a page can have? Pages with unique content often perform the best in Google's search results, are better for users, which in turn, is probably better for your business.
Your best bet in this situation is to create useful and unique content for each page. How? Well, take a look at some of the major local portals and see how much effort they put into their localized pages.
But would you consider these to be doorway pages? Google defines a doorway page as:
Doorway pages are typically large sets of poor-quality pages where each page is optimized for a specific keyword or phrase. In many cases, doorway pages are written to rank for a particular phrase and then funnel users to a single destination.
Forum discussion at Google Groups.