What was the role of imperfect local information in the growth, gender gap, and STEM (Science, Technology, Engineering and Math) major selection of early 20th century American universities? In order to examine pre-1950 American higher education, this study constructs four rich panel datasets covering most students, high school teachers, and doctors in the state of California between 1893 and 1946 using recently-digitized administrative and commercial directories. Students attending large California universities came from more than 600 California towns by 1910, with substantial...