by Jean Roth , jroth@nber.org , 2014-06-11 http://www.census.gov/prod/cen2010/doc/sf1.pdf : ------------------------------------------------ Internal point- The Census Bureau calculates an internal point (latitude and longitude coordinates) for each geographic entity. For many geographic entities, the internal point is at or near the geographic center of the entity. For some irregularly shaped entities (such as those shaped like a crescent), the calculated geographic center may be located outside the boundaries of the entity. In such instances, the internal point is identified as a point inside the entity boundaries nearest to the calculated geographic center and, if possible, within a land polygon. ------------------------------------------------