Seems like that would be difficult to remember - every postman I've known in the UK just learns the route. It would also be harder for people posting a letter t

Seems like that would be difficult to remember - every postman I've known in the UK just learns the route. It would also be harder for people posting a letter to remember - it's easier to remember 6-7 characters than 12 digits, and less prone to errors. Get one character wrong in a postcode and it'll _probably_ still go to the right region, or be an obvious error and handled accordingly, and if you're written the full address you have the area/city to check. Mistaking 40.6971, -74.2598 for 41.6971, -74.2598 puts you 100km away, and 50.6971, -74.2598 1000km away, and there's no obvious way of telling that's wrong. We can do something similar to your system in the UK now - "10 SW1A 2AA" is a unique address, but we don't as it's less robust. "10 Downing Street, London, SW1A 2AA" makes the intention clearer, both if there is an error when writing ("10 Downng Street, Lendon, W1A 2AA" - we can make a fair assumption, particularly if the name indicates it's the same as other mail going there) or if it is damaged in transit ("10 Downing [Unreadable], London, SW-- 2A-").