The impact of the COVID-19 pandemic on emergency department (ED) visits in the United States was analyzed using data from the National Syndromic Surveillance Program (NSSP). During the early pandemic period (March 29–April 25, 2020), the total number of ED visits was 42% lower than during the same period in 2019. The largest declines were observed in children aged ≤14 years, females, and the Northeast region. The proportion of ED visits related to infectious diseases increased significantly, with a prevalence ratio of 3.79 for infectious disease-related visits during the early pandemic period compared to the comparison period. The study found that visits for conditions such as abdominal pain, musculoskeletal pain, and essential hypertension decreased, while visits for infectious diseases, including COVID-19, increased. However, visits for life-threatening conditions such as acute myocardial infarction also declined, suggesting some individuals may have delayed care. The analysis also showed that the number of visits for conditions like cardiac arrest and ventricular fibrillation increased during the early pandemic period. The findings indicate that the pandemic significantly altered ED use, with the highest declines in regions where the pandemic was most severe. The study highlights the need for public health measures to address concerns about ED visits during the pandemic, including the continued use of virtual visits and adherence to infection control guidelines. The study also notes limitations, including potential misclassification of diagnostic categories and non-uniform coverage across states. Overall, the pandemic has had a substantial impact on ED visits, with significant decreases in certain populations and conditions, and increased visits for infectious diseases. Public health efforts should focus on ensuring access to care for serious conditions and addressing concerns about infection risk in EDs.The impact of the COVID-19 pandemic on emergency department (ED) visits in the United States was analyzed using data from the National Syndromic Surveillance Program (NSSP). During the early pandemic period (March 29–April 25, 2020), the total number of ED visits was 42% lower than during the same period in 2019. The largest declines were observed in children aged ≤14 years, females, and the Northeast region. The proportion of ED visits related to infectious diseases increased significantly, with a prevalence ratio of 3.79 for infectious disease-related visits during the early pandemic period compared to the comparison period. The study found that visits for conditions such as abdominal pain, musculoskeletal pain, and essential hypertension decreased, while visits for infectious diseases, including COVID-19, increased. However, visits for life-threatening conditions such as acute myocardial infarction also declined, suggesting some individuals may have delayed care. The analysis also showed that the number of visits for conditions like cardiac arrest and ventricular fibrillation increased during the early pandemic period. The findings indicate that the pandemic significantly altered ED use, with the highest declines in regions where the pandemic was most severe. The study highlights the need for public health measures to address concerns about ED visits during the pandemic, including the continued use of virtual visits and adherence to infection control guidelines. The study also notes limitations, including potential misclassification of diagnostic categories and non-uniform coverage across states. Overall, the pandemic has had a substantial impact on ED visits, with significant decreases in certain populations and conditions, and increased visits for infectious diseases. Public health efforts should focus on ensuring access to care for serious conditions and addressing concerns about infection risk in EDs.