At the same time, visits to ERs have gone up by 30 percent.
The study looks at the closures from 1990 to 2009 in non-rural areas. Most were in for-profit hospitals in more competitive markets.
Also, ER departments in areas with more poverty were more likely to shutter than those is economically secure communities.
Some ERs are reporting difficulty keeping specialty doctors because the don't want to do emergency work, especially for poorly insured patients.