I began adding US metro areas last night as "economic region" (RGNE). The table I was drawing from was here: http://en.wikipedia.org/wiki/Table_of_United_States_Core_Based_Statistical_Areas. These are agglomerations of populated areas that have begun to assume a cohesive entity for local description purposes and population size (i.e. Tampa Bay for the cities close to Tampa, FL). Generally this has nothing to do with administrative division. I was wondering if economic region RGNE was the correct feature code or maybe PPLS would be a better code? I wasn't quite sure the semantics of those.