Answer:
I'd say 100 m
Explanation:
If 1 inch = 50 miles, all you really have to do is measure the line by inches. When I measure it in full-screen, it's about 2 inches.

Also, if you're not sure, that line is too long to be just and inch.
*The length of your tip to your knuckle on your thumb is about an inch.
HOPE THIS HELPS!!!