posted by Mikal .
What is the difference between geographic midpoint and the midpoint calculated by halving the distance between two cities?
Also, is Georaphic midpoint significantly different that the average longitutdes and latitutdes of two different locations?
A geographic midpoint is somewhere along a great circle between two cities. The distance to that point will be half the total distance.
The location of the geographic midpoint can be much difference than the average latitude and longitude, if the points are far apart compared to the radius of the Earth. For example, between Las Vegas and Tehran, Iran, the Geographic midpoint is the North Pole.