Washington, D.C., Maryland and New Jersey are the only areas in the U.S. with more than 20 ASCs per 1,000 square miles, according to a July report from Anthem's Public Policy Institute.
Totals were calculated using data from the Ambulatory Surgery Center Association and the U.S. Census.
The number of ASCs per 1,000 square miles:
More than 20:
Washington, D.C.
Maryland
New Jersey
Five to 20:
California
Hawaii
Massachusetts
Connecticut
Rhode Island
Pennsylvania
Georgia
Florida
One to four:
Washington
Arizona
Colorado
Wisconsin
Illinois
Indiana
Michigan
Ohio
Missouri
Arkansas
Tennessee
Louisiana
Mississippi
Texas
South Carolina
North Carolina
Virginia
New York
New Hampshire
Delaware
Less than one:
Alaska
Oregon
Idaho
Nevada
Utah
Montana
Wyoming
New Mexico
North Dakota
South Dakota
Nebraska
Kansas
Oklahoma
Minnesota
Iowa
Kentucky
West Virginia
Alabama
Vermont
Maine