Anonymous asked: how long are the white dahes on a highway?
Well, it varies, of course. But most states follow the U.S. Federal standard, which states that each white dash should be 10 feet long, with a 30-foot gap between dashes (as specified in Section 634 of the “Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects” published by the U.S. Department of Transportation’s Federal Highway Administration).
Now, if you consider that a mile contains 5,280 feet, and that one dashed line occurs every 40 feet, that means that each mile of dotted line on a U.S. federal highway contains exactly 132 white dashes.
(I know you didn’t ask how many dashes are in a mile, but I just kind of threw that in as a bonus.)