Although usually conceived of and studied as individual types, genres are frequently combined in practice. This research examines how genres are combined in popular American films, and how the popularity of particular combinations changed between 1946 and 2013. Distinguishing between “contextual genres” (which identify a film's subject matter) and “affective genres” (which identify a film's intent), we find marked differences between the postwar and blockbuster eras of the Hollywood film industry. The blockbuster era exhibits less generic diversity than the earlier postwar era. Furthermore, the popular postwar‐era films dealt with serious subjects and were set in realistic settings. The blockbuster era replaced these with intense, nonrealistic films. We also find that the relationship between contextual and affective genres changes within industry eras, with affective genres dominating at the beginning of new periods and the popularity of contextual genres growing as the period progresses.