ZIP Code Distance Database -- ZIP Code Tabulation Area (ZCTA) Distance Database
If the size of the full data file is too large and distances for only a handful of ZIPs is required, then running the calculations for the necessary ZIP codes only using the ZCTA centroid data file might be one helpful approach.
Jean Roth created the SAS, Stata, and CSV distance files to make the data easier to use.
The size of the file increases with the radius. Smaller files (<= 25 or <= 50 miles) may be easier to use if only ZIP Code distances <= 25 or <= 50 miles respectively are needed. The ∞ has all combinations of ZIP Codes.
To report problems or if you have comments or suggestions , e-mail Jean Roth at firstname.lastname@example.org