McCray grew up in rural southwestern Pennsylvania and later attended graduate school at the University of Arizona. He is the author of four books on the history of science and technology; topics include the effects of technology on astronomical practice, the activities of amateur scientists during the Cold War, and activities of scientists who promoted radical visions for the technological future. In 2005, McCray co-founded the Center for Nanotechnology in Society  with a grant from the National Science Foundation and leads a research group focusing on the history of nanotechnology. In 2011, he was elected a Fellow of the American Association for the Advancement of Science. McCray's 2013 book The Visioneers won the 2014 Watson Davis and Helen Miles Davis Prize  from the History of Science Society.