Family size composition differentials between central city-suburb and metropolitan-nonmetropolitan migration streams.

During the migration intervals 1965-19709, 1970-1975, and 1975-1979, families that migrated from Standard Metropolitan Statistical Areas (SMSAs) to nonmetropolitan areas and from central cities to suburban rings were larger in mean size than families that composed the respective counterstreams. Mean family sizes declined sharply for all groups throughout the period, but absolute differentials between opposing streams increased slightly. In terms of the selective attraction of families by size, nonmetropolitan net in-migration was very similar to suburbanization within SMSAs. A considerable portion of recent nonmetropolitan net gains resulted from the exchange of larger in-migrant families for smaller out-migrant families.