The FedEx problem

The original shipping strategy of FedEx is to fly all packages to a hub location during the afternoon and evening, sort them there, and then fly them to their destinations during the night for delivery the next day. This leads to interesting mathematical questions: Given a population represented by points in Euclidean space or on a sphere, what is the location of the point of the hub that minimizes the total distance to all the points? Is such a point unique? Then using census data from 2000 we examine how close the FedEx hub in Memphis is to the hub for the U.S. population.