Porque o proceso de mecanizacion e racionalizacion da agricultura se paralizou nalgun momento da historia e, en consecuencia non houbo un proceso de urbanizacion maior. Park o explicaba asi en 1942:
The mechanization and rationalization of agriculture, for instance, has tended to depopulate the countryside, and by converting the farmsted into a factory and the peasant into a wage earner and proletarian, has so stepped up the tempo of rural life that is has brought society as a whole into such a condition of unstable equilibrium that anything apparently may happen, the best as easily the worst (Par, 1942:232)
