Contemporary discussions claim high and increasing diversity, but analyze few actual trends.
This paper examines completed family size diversity from 1940 to 2000 by race and across US states. For all groups, regions and the USA as a whole, family size diversity decreased significantly, produced by a combination of fewer small and large families and a general decline in regionally-based differences. Both within and across states the diversity declined in two stages, but regional clusters of states followed different paths. A cluster of Southern Mountain states showed the greatest contrast. Between the 1940s and the early 1970s, a slight baby boom rise in diversity among homogeneous states, was counterbalanced by declining diversity in more diverse states.