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Comment by merek | Hacker News Reader

If I understand correctly, Toronto, Sydney, Melbourne, Mexico City, Tehran and St Louis have a majority streets running slightly askew from due North - South or due East - West. Any ideas why that may be the case?

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Another tidbit about Melbourne (I'm a fan): while most of greater Melbourne orients ~8 degrees clockwise of true north, the Hoddle Grid right in the middle and South Melbourne instead orient ~20 degrees counterclockwise of true north, in order to align with the adjacent stretch of the Yarra River.

Naturally, as a lifelong resident, I lean 8 degrees to the right when reading any map.

Ooh. I would never had noticed. And now I can't unsee it!

Toronto is aligned to the long straight stretch of Lake Ontario's Northern shore:

https://en.wikipedia.org/wiki/Lake_Ontario#/media/File:ISS-3...

I found a promising answer in a comment from "Nathan":

> Most of Melbourne’s grid was laid out according to magnetic north, not true north, hence the ~8 degree rotation.

And Melbourne is too lazy to update their streets as the magnetic north moves.

Couldn’t they just rotate their continent? It is an island, after all.

They try but people in Sydney keep rotating it back.

Mexico City was originally on an island [1]. I wonder if, like Manhattan, that has something to do with it.

[1] https://en.wikipedia.org/wiki/Tenochtitlan#/media/File:Paint...)

Could be a variety of reasons. Maybe they point to geographic north instead of magnetic north, or it could be just simple measurement error when the city was constructed, or a natural feature of the terrain, similar to the Manhattan and Detroit graphs

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