Importance Disaster exposure is associated with the development of posttraumatic stress (PTS) symptoms in youths. However, little is known about how to predict which youths will develop chronic PTS symptoms after disaster exposure. Objective To evaluate PTS symptom trajectories among youths after 4 major US hurricanes and assess factors associated with those trajectories. Design, Setting, and Participants This cohort study used integrative data analysis to combine data from 4 studies of youths’ responses to natural disasters (hurricanes Andrew , Charley , Ike , and Katrina ) at time points ranging from 3 to 26 months after the disasters. Those studies recruited and surveyed youths aged 6 to 16 years at schools via convenience sampling of schools near the path of destruction for each hurricane. This study was conducted from August 2017 to August 2020, and pooled data were analyzed from February 2019 to October 2020. Exposure Experience of a natural disaster during the ages of 6 to 16 years. Main Outcomes and Measures Posttraumatic stress symptoms were assessed using the University of California, Los Angeles, Posttraumatic Stress Disorder Reaction Index (UCLA PTSD-RI) and the UCLA PTSD-RI-Revised. Latent class growth analyses were used to evaluate the youths’ PTS symptom trajectories and associated factors. Results Among 1707 youths included in the study, the mean (SD) age was 9.61 (1.60) years, 922 (54%) were female, and 785 (46%) self-identified as White non-Hispanic. Four PTS symptom trajectories were identified: chronic (171 participants [10%]), recovery (393 [23%]), moderate-stable (563 [33%]), and low-decreasing (580 [34%]). Older youths were less likely to be in the chronic group; compared with the chronic group, each 1-year increase in age was associated with increased odds of being in the other groups (recovery: odds ratio [OR], 1.78 [95% CI, 1.29-2.48]; moderate-stable: OR, 1.94 [95% CI, 1.43-2.62]; and low-decreasing: OR, 2.71 [95% CI, 1.99-3.71]). Compared with males, females had higher odds of being in the chronic group than in any other group (recovery group: OR, 0.48 [95% CI, 0.26-0.91]; moderate-stable group: OR, 0.37 [95% CI, 0.21-0.64]; and low-decreasing group: OR, 0.25 [95% CI, 0.14-0.44]). Conclusions and Relevance In this cohort study, few youths reported chronic distress, and trajectories among most youths reflected recovery or low-decreasing PTS symptoms. Older age and identification as male were factors associated with decreased odds of a chronic trajectory. Youths with chronic or moderate-stable trajectories may benefit from intervention.