How Can I Calculate Distances For a Dealer Locator Application?
In order to simplify the distance calculations between two points our Zip Source U.S. product converts conventional latitude/longitude measures into X and Y coordinates. This conversion simplifies distance calculations for you by allowing you to utilize a basic formula - The Pythagorean theorem - for calculating point to point distances instead of the more complicated Great Circle distance calculation formulas.
We provide you with the most complete and accurate set of geographic data possible. We minimize the distortion which occurs when a curved surface is represented on a flat plane (via X Y coordinates) by using an Albers projection to generate the X Y coordinates contained in Zip Source U.S.
On ZIPSOURCE, each ZIP Code or place name is assigned latitude / longitude coordinates and within the 48 continental United States is also assigned a pair of arithmetic coordinates. These coordinates are tied to the center point of the ZIP Code called the ZIP Centroid. The Pythagorean theorem can be applied to these coordinates to calculate the straight line distance between two points. You can calculate the straight line distance by computing the hypotenuse of a triangle formed by the two known X Y coordinates and your destination
The Albers Projection
The arithmetic X Y coordinates result from the conversion of latitude and longitude coordinates using the Albers Equal-Area Conic projection formulas developed for us by IBM. This logic is based on Clark's ellipsoid of 1866. The point where X and Y coordinates are calculated from is approximately 5,000 miles East of Longitude 96 and latitude 24.