There is no such thing as a "linear mile." The term "mile" itself already implies a linear measurement, representing a distance along a straight line.

It's possible that you might have heard or seen the term used incorrectly in some contexts, but it's not a standard or recognized unit of measurement.

If you're looking for a specific type of mile, you might be thinking of:

* Nautical mile: This is a unit of measurement used in navigation and is equal to 1.1508 statute miles (land miles).

* Statute mile: This is the most common type of mile used in the United States and is equal to 5,280 feet.

If you can provide more context about where you encountered the term "linear mile," I might be able to help you understand what it was referring to.