Introduction: Politics are a major source of stress and anxiety among U.S. adults, and the 2016 U.S. general election may have led to increased psychosocial stress among different racial/ethnic populations. Psychosocial stress can manifest physiologically in elevated blood pressure (BP). Yet, little is known regarding whether this response differs among racial/ethnic groups. We sought to characterize population-level changes in BP among non-Hispanic (NH) Whites, NH Blacks, and Mexican Americans before and after the 2016 U.S. general election. Methods: Using cross-sectional 2015-2018 National Health and Nutrition Examination Survey (NHANES) data, we included participants aged ≥20 years with ≥1 systolic BP (SBP) and diastolic BP (DBP) measurement during the examination periods just prior to and after the election. The pre-election period was from May 2016 to October 2016 and the post-election period was from November 2017 to April 2018. Survey-weighted data were analyzed to compare mean SBP and DBP pre- and post-election, stratified by race/ethnicity. Stratified analyses were also performed on hypertension status, defined as self-report, mean BP ≥140/90, or use of ≥1 antihypertensive drug. Results: We included 1,060 NH Whites, 720 NH Blacks, and 223 Mexican Americans during the pre-election period and 676 NH Whites, 564 NH Blacks, and 468 Mexican Americans during the post-election period. We observed a significant increase in SBP among Mexican Americans (mean±SEM, 118±0.5 mmHg [pre-election] vs. 121.7±0.7 mmHg [post-election], p=0.005), but not among NH Blacks (126.7±0.9 mmHg vs. 128.9±0.7 mmHg, p=0.083) nor NH Whites (123±0.6 mmHg vs. 124.8±1.4 mmHg, p=0.256). DBP increased among both Mexican Americans (69.5±0.5 mmHg vs. 72.6±1.1 mmHg, p=0.022) and NH Blacks (72.2±0.8 mmHg vs. 74.9±0.6 mmHg, p=0.012), but not among NH Whites (70.4±0.4 mmHg vs. 72.9±1.3 mmHg, p=0.075). These effects were largely attributable to BP changes among those with hypertension (pre-election: 414 NH Whites, 350 NH Blacks, 60 Mexican Americans; post-election: 330 NH Whites, 298 NH Blacks, 156 Mexican Americans), in whom there was an increase in SBP among NH Blacks (138.8±1.3 mmHg vs. 143.7±1.7 mmHg, p=0.032) and Mexican Americans (133.9±1.1 mmHg vs. 141.9±1.5 mmHg, p=0.0002); and an increase in DBP among NH Blacks (76.2±1.2 mmHg vs. 80.8±0.9 mmHg, p=0.005). No significant changes were observed in any racial/ethnic group without hypertension. Conclusions: At the population-level, NH Blacks and Mexican Americans had increases in BP following the 2016 U.S. general election, largely driven by BP elevations among those with hypertension. Patient-level data, especially linked with political affiliation, may provide additional insights into the psychosocial stress effect of major political events.