The encyclopedia · Software & IT · Operational decision · 1959–1974
The UK postcode encoded the sorting route so machines could sort mail
Royal Mail's two-part postcode puts the sorting office in the outward code and the street in the inward code, so mail routes itself and sorts 20 times faster.
Royal Mail
the move
In the late 1950s the General Post Office's electro-mechanical sorting machines still needed an operator to remember which bin each place went into. The fix was to put the answer on the envelope itself.
Norwich received the world's first postal codes designed for machine sorting in October 1959: 150,000 addresses were coded, and the six-character format mixed letters and digits. National roll-out followed and was completed in 1974, as both the trade press and official records confirm.
The design made automation cheap. A postcoded letter is sorted about 20 times faster and more accurately than by hand, with machines handling around 30,000 items an hour, because the outward code routes it to the right area and the inward code to the right street. The same codes later became census geography, route-planning destinations, and address lookup keys.
why it works
- The code carries the sorting decision, so operators need no geography memory.
- The two-part structure lets coarse sorting happen early and fine sorting later.
- Alphanumeric codes fit mechanical readers and stay compact.
- The Postcode Address File turned codes into a general address key.
what transfers
If a process depends on human memory, move the knowledge into the artifact: encode the routing decision in the data itself, and the machine only has to read what is already there.
what came after
The UK postcode became a national address standard used for insurance, navigation, and statistics and inspired postal codes worldwide. Royal Mail's database holds about 1.67 million postcodes covering 24.5 million addresses.
references
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