1. A system for determining and generating an optimal map projection for a geographical extent, the system comprising: a computer system comprising: one or more computer processors, one or more computer-readable storage media, and program instructions stored on one or more of the computer-readable storage media for execution by at least one of the one or more processors, the program instructions, comprising: accepting a user request for a map for a geographical extent for display using a computer; determining a set of elements that are contained within the geographical extent, using the computer; building a list of shape files for the elements, each shape file being constructed based on a map projection; ranking the shape files by comparing an area of the shape file to a geographical area of the shape file's associated element; re-rank the shape files by comparing a great circle distance between a center of the area of the shape file and a geographical center of the shape file's associated element; re-rank the shape files by comparing azimuth errors for a set of contained points in the shape associated with each of the shape files; and selecting a map projection that minimizes differences in area and distance as compared to the geographical extent.