Increasingly, patients admitted to U.S. hospitals from the emergency department (ED) wait for hours—or, sometimes, days—before a bed becomes available. In the meantime, these “boarders” typically remain in the ED, where they occupy beds that would otherwise be used to evaluate and treat new patients, reducing available capacity.

The American Hospital Association reported in 2009 that half of urban hospitals and 38% of all hospitals are at or over capacity in their emergency department. A quarter of all hospitals and 45% of metropolitan hospitals experienced overcrowding at a level that led to ambulance diversion. "According to a 2009 report by the GAO, “lack of access to available beds in the hospital for admitted patients is the main factor contributing to emergency department crowding.”

The number of hospital beds has declined by more than 198,000 over the last 15 years, even as population growth and other factors pushed demand for ED services up 37%. Since 44% of hospital admissions originate in the ED, bed availability, boarding, and ED overcrowding are inextricably intertwined.