For example: Any letters I received pre-1964, (perhaps containing a decoder ring or a birthday card from my godmother with a buck in it--quite a generous gift, that buck would buy four packs of Pall Malls or 20 Nestle's Crunch bars) would have been addressed like this:
6810 Wakefield Ave.
Cleveland 2, Ohio
Our mailman (back then, all letter carriers were men, so there was nothing else to call them) and about thirty others--all of them working out of the branch PO for Zone 2--couldn't start sorting the mail for their routes until other sorters, located in the branch and working the graveyard shift, sorted them down to the thirty-some piles for the individual routes The only tool available was that two-digit ZONE number. The entire City of Cleveland could have no more than 99 zones. Once the ninety nine piles were sorted by zone number, everything else depended on knowing which street and which block was in which route.
The U.S. Post Office in Washington had bright staff who researched all the possible methods of getting a zone-coding system with greater finesse at locating a building, on a street, in a neighborhood, in a zone in a city in a state, all by looking only at the Postal Code Zone.
They looked and looked. They noted what the Brits had, looked at what the Canadians were considering, and checked out what Cuba had. Cuba did not make the cut, as it had a system that delivered letters addressed like this: "...near the corner of Avenida Zanha and Calle Rayo".
The Post Office recommendation in '63, made by the esteemed Postmaster General, John A. Gronouski--a good Kennedy Democrat from Wisconsin--called for a six-digit indicator, using twin alpha-numeric sets of three, with alternating numbers and letters (A2B 3C4) that would produce a huge range of combinations, allowing an indicia sufficiently versatile that it could sort mail into some very fine categories.
For Example, A piece of mail coded A3X 7P4 could have enough precision to indicate the address was:
o In a specific zone
o On specific mail delivery route
o On an urban block
o In a specific apartment block or commercial building
o On a specific floor
It was being used-- after having been perfected--in at least two places: Great Britain and the Netherlands. And everybody LIKED IT A LOT. And many other countries were studying it.
Enter: The United States Congress.
Congress listened, deliberated, blustered, horse-traded, groaned, log-rolled, strained, compromised, eye-gouged, and finally forged an agreement among the august membership.
And Congress Spoke:
The American People will not tolerate, will not accept, will not use six digits, especially with those confusing letters of the alphabet mixed in. The American people will accept only a system of zone codes with no more than five numbers... and no alphabet soup.
Moreover, the American people will happily endorse and adapt to the use of Zipcode. In order to soften the body blow inherent in drastic change, the American people will have the ministrations of Mr. ZIP to help them acclimate to the this new and complex system, which will be--because we have decreed it--the best mail sorting system in the world.
These are the same fools who are designing a health care system, getting right down to the minutia, for the American people. They're doing it in committees and caucuses and eye-gouging, log-rolling, horse-trading confabs from now until the last lobbyist has been shook down.
They know what the American people want. They know what we need. They've undertaken similar delicate, difficult tasks with reasonably good results. And if they do not get it right the first time, they know that a little tweaking cum eye-gouging sometime in the future is always possible.
After twenty years of Mr. ZIP (a backronym for Zone Improvement Program) the US Postal Service tweaked the marginally useful ZIPcodes with ZIP plus 4. Congress no longer has any say in postal affairs, as it is now (since 1972) an Independent Agency of the U.S. Government, not funded by taxes, not run by Congress.
But is still saddled with what the US Congress did in creating the Zone Improvement Program.