Do metropolitan areas mean anything? A research note

"In this brief study, I ask the most elementary question about the coherence of [U.S.] central cities and suburbs: are their population changes correlated in any simple way?...Specifically, I ask the following question: suppose one knows the national population growth rate, whether an SMSA component is the central city (cities) or suburbs, and the region in which the SMSA is located, then would the ability to explain the component's population growth rate be improved by knowing which SMSA the component is in?... The conclusion is that there appears to be an SMSA effect on population growth."