Between 2001 and 2006, the number of visits paid to emergency rooms in the United States increased annually by nearly 12 million, according to a U.S. Government Accountability Office report released in April 2009. In addition, the average time ER patients waited before being seen by a physician rose from 46 minutes in 2003 to 56 minutes in 2006. Although fewer hospitals reported having to divert ambulances to other facilities because of overcrowding, those that did reported spending more hours on average on diversion. Overcrowding in emergency departments is attributed to a shortage of critical care inpatient beds, delaying the transfer of stabilized emergency patients to non-emergency units.

The federal Emergency Medical Treatment and Active Labor Act (EMTALA), passed by Congress in 1986, contributed to the growing pressure on emergency rooms by requiring every hospital participating in the federal Medicare and Medicaid programs (virtually all) to screen and stabilize any person who seeks help, regardless of his ability to pay. Because the government didn't provide funding for this mandate, many ERs have a problem with uncompensated care. The poor, the elderly and people with chronic conditions are the heaviest users of ERs. But ERs also help fill regular hospital beds and contribute to some hospitals' profitability. In 2006, half of all non-obstetric hospital admissions came through the emergency department. Updated February 2010