Key PointsQuestionDid patterns of US emergency department (ED) visits and mental health (MH)–related ED visits change during the COVID-19 pandemic?FindingsIn this cross-sectional study with 1570 total observations for January 1, 2019, to December 31, 2021, mean total ED visits decreased more than the proportion of ED visits for MH conditions during the weeks after the pandemic was declared in 2020 compared with the corresponding weeks in 2019. The mean proportion of MH-related ED visits increased from 8% in 2019 to 9% in 2020 and then decreased to 7% in 2021, when mean total ED visits rebounded more than MH-related visits.MeaningThe finding that ED visits for MH decreased less than visits for other reasons during the pandemic suggests that patients with non-MH conditions may have greater flexibility during public health emergencies, whereas there may be fewer alternatives for MH care.