Why shouldn't aviation switch from magnetic to true north?

[AuntPeggy]

Here in the midwest you don't need a compass. There are so many roads that run north/south and east/west, you're fine without a compass.

Magnetic? or true?

 

[EdFred]

Magnetic? or true?

Close enough to the agonic that it doesn't matter.

 

[flyingcheesehead]

Magnetic? or true?

The roads are true, otherwise we'd have to tear 'em all up and repave 'em every few years.