Proximity Searches

[Sunshein]

What is the reference data used to search mileage proximities from a given point? I see store and restaurant web sites allowing searches of their business locations within set mileage distances. What is the basis for that search or find capability?

[sbg2]

See if the following article helps... http://ask.metafilter.com/52954/Zip-Code-Proximity-Search

Its based on zip codes but might be a good starting point.