Prior studies suggest that the COVID-19 pandemic was associated with decreases in emergency department (ED) volumes, but it is not known whether these decreases varied by visit acuity or by demographic and socioeconomic risk factors. In this study of more than one million non-COVID-19 visits to thirteen EDs in a large St. Louis, Missouri, health system, we observed an overall 35 percent decline in ED visits. The decrease in medical and surgical visits ranged from 40 percent to 52 percent across acuity levels, with no statistically significant differences between higher- and lower-acuity visits after correction for multiple comparisons. Mental health visits saw a smaller decrease (-32 percent), and there was no decrease for visits due to substance use. Medicare patients had the smallest decrease in visits (-31 percent) of the insurance groups; privately insured (-46 percent) and Medicaid (-44 percent) patients saw larger drops. There were no observable differences in ED visit decreases by race. These findings can help inform interventions to ensure that people requiring timely ED care continue to seek it and to improve access to lower-risk alternative settings of care where appropriate.