The "distance as the crow flies" is a way to describe the distance between two locations without considering all the variable factors. As an example, travelling from California to Maine involves a rather indirect route around, over and through mountain ranges and so forth. The driving distance might be about 3,500 miles, but the distance "as the crow flies" is about 2,800 miles.
Why is there such a big difference? The crow flies in a straight line, while drivers have to follow the roads whichever way they twist and turn. The crow always flies in a straight line, so telling a distance is much easier using the crow than the car.
Visit a website that offers a distance calculator. Google maps, at maps.google.com, has an easy method for finding the distance as the crow flies.
On the bottom of the map, next to the distance legend is a ruler icon. Click the ruler icon to open up the distance calculator.
Click on the unit's drop-down menu. Select a unit of measure by which you want Google to report the total distance. This distance can be changed even after the line is drawn.
Zoom in to the starting point, or just click on the map in the general area where the line should begin. Click on the map again to mark the end point. A red line will appear. The final result appears on the left side of the screen.
Click on the map again to add more waypoints. The map line can turn in any direction as many times as necessary. However, an end point can never fall on the red line.
With each line, the distance will automatically update.
The "Zoom" and "Scroll" functions still work in the distance calculator mode. There is an option to "delete last point" if a mistake is made. This option can be used as many times as needed or until no points exist any longer on the map