I understand that the post is more about the USPS holding onto something seemingly trivial. Kinda like when we tell google to block out certain places of security. But we already have so many ways to get around it, like going there and taking a picture, or renting a plane, who knows. Or the Streisand Effect kicks in and everything is a mess.
At any rate, I have had to do a lot with zip codes in the past, long before anything like an API was a common term let alone something every company was happy to let you hook into and use their services. Heck, this was back when it costs a few grand to take CC's on a website and had to deal with that awful Authorienet API. That used to be thought of as crazy talk. Now we have amazing stuff like this: http://www.geonames.org
At any rate, I have had to do a lot with zip codes in the past, long before anything like an API was a common term let alone something every company was happy to let you hook into and use their services. Heck, this was back when it costs a few grand to take CC's on a website and had to deal with that awful Authorienet API. That used to be thought of as crazy talk. Now we have amazing stuff like this: http://www.geonames.org