Is the US zip code centered on 2 zip codes?

Question

How can I determine the closest "central" zip code between the two specified US ZIP codes?

Answer 1

• match zip codes with latitude / longitude (google returned http://www.boutell.com/zipcodes/ )
• calculate the geographic midpoint between two coordinate pairs (e.g. http://www.geomidpoint.com/calculation.html )
• Find the closest zip code for the resulting coordinate.