History is irrevelant here. I'm sure you know that our population has grown exponentially since the 1950s.
http://aging.senate.gov/crs/aging4.pdf
The U.S. population has experienced remarkable growth since 1950. From a base of about 152
million Americans in 1950, an additional 155 million persons were added to the population
between 1950 and 2009, with the number of additional women slightly outnumbering additional
men (see Figure 1). This increase (of about 105%) in the size of the U.S. population was
remarkable compared with other industrialized countries. Germany and Italy, for instance, grew
by only 21% and 30% respectively during the same period.6 And, a number of countries, most
notably in Eastern Europe, have recently experienced absolute reductions in the size of their
populations.7