 Zinn rejected alternate sites outside the Chicago area, and the Army found a new site for the laboratory's permanent home about away in DuPage County, Illinois, which became known as Site D.

Under Zinn, the Argonne National Laboratory adopted slightly more progressive hiring practices than other contemporary institutions.Three African American women and seven men, six of whom had worked on the Manhattan Project, were employed in research at Argonne at a time when the Los Alamos National Laboratory had no African American scientists.Argonne also appointed women to positions of authority, with Maria Goeppert-Mayer as a section leader in the theoretical physics division, and Hoylande Young as director of the technical information division.