Importance: In 2022, the US Supreme Court abolished the federal right to abortion in the Dobbs v Jackson Women's Health Organization decision. In 13 states, abortions were immediately banned via previously passed legislation, known as trigger laws., Objective: To estimate changes in anxiety and depression symptoms following the Dobbs decision among people residing in states with trigger laws compared with those without them., Design, Setting, and Participants: Using the nationally representative repeated cross-sectional Household Pulse Survey (December 2021-January 2023), difference-in-differences models were estimated to examine the change in symptoms of depression and anxiety after Dobbs (either the June 24, 2022, Dobbs decision, or its May 2, 2022, leaked draft benchmarked to the baseline period, prior to May 2, 2022) by comparing the 13 trigger states with the 37 nontrigger states. Models were estimated for the full population (N = 718 753), and separately for 153 108 females and 102 581 males aged 18 through 45 years., Exposure: Residing in states with trigger laws following the Dobbs decision or its leaked draft., Main Outcomes and Measures: Anxiety and depression symptoms were measured via the Patient Health Questionnaire-4 ([PHQ-4]; range, 0-12; scores of more than 5 indicate elevated depression or anxiety symptoms; minimal important difference unknown)., Results: The survey response rate was 6.04% overall, and 87% of respondents completed the PHQ-4. The population-weighted mean age was 48 years (SD, 17 years), and 51% were female. In trigger states, the mean PHQ-4 scores in the baseline period and after the Dobbs decision were 3.51 (95% CI, 3.44 to 3.59) and 3.81 (95% CI, 3.75 to 3.87), respectively, and in nontrigger states were 3.31 (95% CI, 3.27 to 3.34) and 3.49 (95% CI, 3.45 to 3.53), respectively. There was a significantly greater increase in the mean PHQ-4 score by 0.11 (95% CI, 0.06 to 0.16; P < .001) in trigger states vs nontrigger states. From baseline to after the draft was leaked, the change in PHQ-4 was not significantly different for those in trigger states vs nontrigger states (difference-in-differences estimate, 0.09; 95% CI, -0.03 to 0.21; P = .15). From baseline to after the Dobbs opinion, there was a significantly greater increase in mean PHQ-4 scores for those in trigger states vs nontrigger states among females aged 18 through 45 years (difference-in-differences estimate, 0.23; 95% CI, 0.08 to 0.37; P = .002). Among males aged 18 through 45 years, the difference-in-differences estimate was not statistically significant (0.14; 95% CI, -0.08 to 0.36; P = .23). Differences in estimates for males and females aged 18 through 45 were statistically significant (P = .02)., Conclusions and Relevance: In this study of US survey data from December 2021 to January 2023, residence in states with abortion trigger laws compared with residence in states without such laws was associated with a small but significantly greater increase in anxiety and depression symptoms after the Dobbs decision.