The spatial diffusion and adoption of rDNA methods, Regional Studies. The 1980 patent granted to Stanley Cohen and Herbert Boyer for their development of rDNA technology played a critical role in the establishment of the modern biotechnology industry. From the birth of this general-purpose technology in the San Francisco Bay area, rDNA-related knowledge diffused across sectors and regions of the US economy. Patent data are used here to track the geography and timing of rDNA technology adoption in US metropolitan areas. Using event history and fixed effects conditional logit models, it is shown how the diffusion of rDNA techniques was influenced by cognitive, geographical and social proximity.