distance between zipcodes

Anon

This isn't really a PHP question, but I was hoping someone here might be able to answer it. I want to be able to find the distance between two zipcodes, and to find all the zipcodes within a given distance of a given zipcode. I've seen this functionality around, and figured there must be an API for it somewhere. I found one or two, but I can't afford them. I need this for a homebrew kindof project. I imagine that perhaps the postal department might release zipcode information for free and the data could be used to determine the distances by writing my own API to utilize it. Can anyone point me in a proper direction, or have any advice?

jordanj

Yeah man.. I know exactly what you are talking about.. I found some code a while back when I was looking for similar functionality on here: http://px.sklar.com/code-pretty.html?code_id=253

I also found a Zip Code Database floating around someplace.. I think it was on the USPS.com site.. I forget where, but I do remember that the data was a few years old. It seems that if you want current data, you need to throw up the $$.. Anywho, Good luck to ya..

Anon

Check out this link:

http://www.oseda.missouri.edu/jgb/ZIP.resources.html

You can find some decent free data sources, but they will probably be ~10 years out of date by the time you read this.

The following supplier is pretty inexpensive, and their information is much more up to date.

http://www.tpsnet.com/html/zipcode.html

Finding all zipcodes "within 10 miles of 12345" is not an easy task. Figuring out "the distance between 12345 and 54321" is a piece of cake.

The following link should also help you get started.

http://aquion.hyperlink.cz/asp/nearest.html

--Robert

Anon

Thanks. As soon as I can afford or find some data, I may try something to make the calculation faster and simpler. At the back of road atlases they'll often times have a table with all the cities as rows and columns. If you want to know the distance between the two you look at the location where the two cross.

The same kind of table would work for zipcodes. It would be simple to make. It would take a long time to build I'm sure, but you'd only have to build it once. So you could find the distance between a given two by selecting the column of one zipcode from the row of the other zipcode. Finding all zipcodes within x number of miles of a certain zipcode would just be selecting zipcode rows where the column of the given zipcode is less than x.

Is this as functional as I'm imagining? Would this be more efficient than other methods? How large do you imagine the cross table would be?

iceberg

Sure, we can get zip + long + lat for all US zip codeds, but what do you do when you need to include the rest of the world? I can not find any available data online with this information.

As far as calculating the neares that is a simple query, but the math is a bit out there you need to calculate a circle in radians and then fine what the variance is in long/lat. Now my head hurts just thinking about it, but the formula is out there for it.

Anon

i'm just working on this and have found these formulas:

D = R * cos-1(sin(lat1) sin(lat2) + cos(lat1) cos(lat2) cos(lon2 - lon1))

Where R is the radius of the earth (3963 miles)
and lat1, lon1 and lat2, lon2 are the two points in radians -- Degrees / 57.296. If you have latitude and longitude, this should give you an approx of distance between the two point. ALso another version which haven't verfied yet:

d = 69.1(squareroot(long1-long2)²⁾ + (.6(lat1-lat2)²⁾⁾