Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
As farm settlement spread westward, area after area exhibited remarkably similar economic and demographic changes, among them, the establishment of a virtually zero growth rate of farm population. At bottom this was due to a shift in farm family fertility from very high to replacement levels, a trend apparent in older areas as early as the beginning of the nineteenth century despite the abundance of good farm land to the west. The principal source of this wholly voluntary adjustment of fertility was the increasing difficulty encountered by farm parents in providing for their children the kind of start in life they would like them to have. Similar pressures may account for other rural fertility declines in the historical past or today's LDC's.