The 'population turnaround' and a model of population change ( USA).

The 'population turnaround', or the reversal of a longstanding US population trend toward growth of cities at the expense of non-metropolitan areas, was first noted in the 1970s, and has since generated a substantial literature, becoming part of the conventional wisdom of American demographics. More detailed analysis of these trends, however, casts doubt on both the novelty and the importance of these reverse flows; much appears to turn on the availability of comparable statistics and the definitions of 'metropolitan' and 'non-metropolitan'. A new model is suggested in which the population of any given county is composed of three components: farm, place, and overspill, each of which may vary more or less independently of the others.-J.R.McDonald