"...about 45 miles...."

We all have been reading about and writing about this race for many years, and still nobody seems to know the exact distance. It is always said to be somewhere between 40 and 45 miles, and the word "about" or "approximate" is usually used. I have even heard estimates from as low as 38 miles to as high as 47.

In these days when everybody has a GPS, it seems like somebody would have a more exact distance, since it is a pretty straight shot from start to finish. A more exact distance would make the elapsed times more meaningful.