OBJECTIVE Rapid access to emergency services is essential for emergency care-sensitive conditions such as acute myocardial infarction, stroke, sepsis, and major trauma. We seek to determine US population access to an emergency department (ED). METHODS The National Emergency Department Inventories-USA was used to identify the location, annual visit volume, and teaching status of all EDs in the United States. EDs were categorized as any ED, by patient volume, and by teaching status. Driving distances, driving speeds, and out-of-hospital times were estimated with validated models and adjusted for population density. Access was determined by summing the population that could reach an ED within the specified intervals. RESULTS Overall, 71% of the US population has access to an ED within 30 minutes, and 98% has access within 60 minutes. Access to teaching hospitals was more limited, with 16% having access within 30 minutes and 44% within 60 minutes. Rural states had lower access to all types of EDs. CONCLUSIONS Although the majority of the US population has access to an ED, there are regional disparities in ED access, especially by rurality. Future efforts should measure the relationship between access to emergency services and outcomes for emergency care-sensitive conditions. The development of a regionalized emergency care delivery system should be explored.