How to find something within X miles of Zipcode?

[mband2000]

I've gone to many dating sites and seen features where you enter your zipcode and you can select an X distance of miles to find members.

How is this done.. I'm not a zipcode guru.. but I'm guessing a certain amount of numbers in the zipcode match a zipcode that's 5 miles away, 10 miles away... ect ect.

If anyone knows how to do this.. I would greatly appreciate your help.

[bpat1434]

I can't say for certain what is happening, but I do know that "21250" is Baltimore, and any 212XX number is Baltimore, Maryland. So, 21250, 21228, 21212, etc etc would be within a few miles (max 10) of eachother...

It is possible to just take each zipcode you want, and then store with it the lat & long of the main USPS hub there. I say that since zips are based on USPS. Then, just evaluate the difference in miles from A to B and if it's less than or equal to your desired distance, include it...

That would be CPU intensive (if you have lots of zips and a large area to cover) but it would get the job done. I'm sure there are commercial packages out there that do this...

[Weedpacket]

Try also searching the forums for the words "zipcode" and "distance"