All USA zip codes split to separate kml files
I was looking and looking for .kml files for USA zip code to display boundraies on google maps with a .kml layer (https://developers.google.com/maps/documentation/javascript/examples/layer-kml)
All I found was a 150MB file from census.gov (https://www.census.gov/geo/maps-data/data/kml/kml_zcta.html)
So I wrote a script that split the giant file to 32,768 separate files each named zip[zipcode].kml
You can download the zip file, unzip it and upload the individual files to your web server (it has to be accecible from google).
Have Fun! Tomer