This paper uses published letters to the editor of major U.S. newspapers to investigate the cultural effects of a major national threat: the September 11, 2001, terrorist attacks. It is based on a hand-coded, stratified random sample of 1,100 letters to the editor published in 17 major papers in the United States (544 pre-September 11, 556 post-September 11). The letters are drawn from a population of 8,101 published letters. Degrees of both authoritarianism and antiauthoritarianism, as well as the general salience of questions of authoritarianism, rose significantly in the post-attack period. The paper suggests that, instead of a simple threat-authoritarianism causal link, authoritarianism and antiauthoritarianism are paired elements of political culture that are invoked together in the face of a national threat.