A Symbiosis of Access: Proliferating STEM PhD Training in the U.S. from 1920-2010.

Over the course of the 20 century, unprecedented growth in scientific discovery was fueled by broad growth in the number of university-based scientists. During this period the American undergraduate enrollment rate and number of universities with STEM graduate programs each doubled three times and the annual volume of new PhDs doubled six times. This generated the research capacity that allowed the United States to surpass early European-dominated science production and lead for the rest of the century.