Why is there a sign on highways that says start measured mile?

Answer 1

These sign are in pairs 'Start of Measured Mile' and 'End of Measured Mile'. The distance has been accurately measured and this enables drivers or other road users to check that their instruments are correctly gauged.

The signs are usually found on fairly level roads, often alongside flat stretches of a river.

Answer 2

The sign "Start Measured Mile" indicates the beginning of a section of highway where drivers can test the accuracy of their vehicle's odometer or GPS. This allows drivers to verify their instruments and ensure they are accurately calculating distance traveled.