Well it depends... are you looking for state prisons or federal?

Federal prisons, there is only one "super-max" facility, and that is ADX Florence in Florence, Colorado.

State prisons, there are a few that are 'super-max'.

Technically speaking, Pelican Bay is a super max, so it is ONE OF the highest security prisons, but it is equal to others.

Here is a (possibly incomplete as of today, print date is previous) listing of supermax prisons in North America:

* U.S. Penitentiary Florence ADMAX (Administrative Maximum) Facility - Florence, Colorado (entirely Supermax)
* United States Penitentiary - Tucson, Arizona
* Holman Correctional Facility - Atmore, Alabama
* ASPC-Eyman, SMU II - Florence, Arizona
* Varner Supermax - Grady, Arkansas
* Pelican Bay State Prison - Crescent City, California
* California State Prison, Corcoran - Corcoran, California
* United States Penitentiary - Atwater, California
* Colorado State Penitentiary - Canon City, Colorado
* United States Penitentiary - Coleman, Florida
* United States Penitentiary - Atlanta, Georgia
* Tamms Correctional Center - Tamms, Illinois
* Wabash Valley Correctional Facility, SHU - Carlisle, Indiana
* Westville Correctional Facility, WCU - Westville, Indiana
* United States Penitentiary - Terre Haute, Indiana
* United States Disciplinary Barracks, Fort Leavenworth, Kansas (military prison)
* Maine State Prison - Warren, Maine
* Maryland Correctional Adjustment Center - Baltimore, Maryland
* Minnesota Correctional Facility - Oak Park Heights - Stillwater, Minnesota
* Mississippi State Penitentiary - Parchman, Mississippi
* Jefferson City Correctional Center-Jefferson City, Missouri
* Northern Correctional Institution - Somers, Connecticut
* Florida State Prison - Raiford, Florida
* United States Penitentiary - Allenwood, Pennsylvania
* Sing Sing Correctional Facility - Ossining, New York
* Ohio State Penitentiary - Youngstown, Ohio
* Idaho Maximum Security Institution - Boise, Idaho
* Oklahoma State Penitentiary - McAlester, Oklahoma
* United States Penitentiary - Lewisburg, Pennsylvania
* Riverbend Maximum Security Institution - Nashville, Tennessee
* Polunsky Unit - Livingston, Texas
* United States Penitentiary - Beaumont, Texas
* Utah State Prison - Draper, Utah
* Wallens Ridge State Prison - Big Stone Gap, Virginia
* Red Onion State Prison - Pound, Virginia
* Ionia Maximum Correctional Facility - Ionia, Michigan
* Mt. Olive Correctional Complex - Fayette County, West Virginia
* Wisconsin Secure Program Facility - Boscobel, Wisconsin
* North Branch Correctional Institution - Cumberland, Maryland
* New Hampshire State Prison - Men - Concord, New Hampshire
* Massachusetts Correctional Institution - Cedar Junction - Walpole, Massachusetts
* Souza-Baranowski Correctional Center- Shirley, Massachusetts
* Attica Correctional Facility - Attica, New York
* Upstate Correctional Facility - Malone, New York


Hope this answers your question.