The loosening of American culture over 200 years is associated with a creativity-order trade-off.

For many years, scientists have studied culture by comparing societies, regions or social groups within a single point in time. However, culture is always changing, and this change affects the evolution of cognitive processes and behavioural practices across and within societies. Studies have now documented historical changes in sexism1, individualism2,3, language use4 and music preferences5 within the United States and around the world6. Here we build on these efforts by examining changes in cultural tightness-looseness (the strength of cultural norms and tolerance for deviance) over time, using the United States as a case study. We first develop a new linguistic measure to measure historical changes in tightness-looseness. Analyses show that America grew progressively less tight (i.e., looser) from 1800 to 2000. We next examine how changes in tightness-looseness relate to four indicators of societal order: debt (adjusted for inflation), adolescent pregnancies and crime, and high school attendance, as well as four indicators of creative output: registered patents, trademarks, feature films produced, and baby-naming conformity. We find that cultural tightness correlates negatively with each measure of creativity, and correlates positively with three out of four measures of societal order (fewer adolescent pregnancies, less debt and higher levels of school attendance). These findings imply that the historical loosening of American culture was associated with a trade-off between higher creativity but lower order.