The Code Project - ZIP Code Utility

The Code Project - ZIP Code Utility

"This article provides an easy method to lookup a U.S. City/State by ZIP Code, or one or more ZIP Codes by City/State. It also describes a method to calculate the distance between two ZIP Codes and find all other ZIP Codes within a radius of X miles of a specified ZIP Code.
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Intrigued by Ben Fry's zipdecode[^] applet, I decided to write a little ZIP Code utility that allows lookups of U.S. locations by ZIP Code, City/State, or all three. Since the data were already in the database in the form of latitude/longitude pairs, I added the capability to find the distance between two points, and to find all other ZIP Codes within a radius of X miles from the original location.
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A disconnected method (i.e. no web service/map point/etc) of determining the distance between two zip codes/locations is something I might be able to use...