Research has linked specific COVID-19-related stressors to the mental health burden, yet most previous studies have examined only a limited number of stressors and have paid little attention to their clinical significance. This study tested the hypothesis that individuals who reported greater COVID-19-related stressors would be more likely to have elevated levels of anxiety, posttraumatic stress symptoms, and serious psychological distress. Methods: An online survey was administered to a convenience sample from 18 June to 19 July 2020, in US states that were most affected by COVID-19 infections and deaths at the time. Individuals who were 18 or older and residents of five Northeast US states were eligible to participate (N = 1079). In preregistered analyses, we used logistic regression models to test the associations of COVID-19 stressors with symptoms on the Generalized Anxiety Disorder-7 (GAD-7), Impact of Event Scale-Revised, and K6, adjusting for sociodemographic covariates. Results: COVID-19-related stressors (i.e., essential worker status, worry about COVID-19 infection, knowing someone hospitalized by COVID-19, having children under 14 at home, loneliness, barriers to environmental rewards, food insecurity, loss of employment) were associated with meeting thresholds (i.e., positive screening) for anxiety, posttraumatic stress, and/or serious psychological distress. Loneliness and barriers to environmental rewards were associated with all mental health outcomes. Limitations: We used a non-probability sample and cannot assume temporal precedence of stressors with regard to development of mental health symptoms. Conclusions: These findings link specific stressors to the mental health burden of the COVID-19 pandemic.