Mayo Clinic () is a nonprofit American academic medical center focused on integrated health care, education, and research. It employs over 4,500 physicians and scientists, along with another 58,400 administrative and allied health staff, across three major campuses: Rochester, Minnesota; Jacksonville, Florida; and Phoenix/Scottsdale, Arizona. The practice specializes in treating difficult cases through tertiary care and destination medicine. It is home to the top-ten ranked Mayo Clinic Alix School of Medicine in addition to many of the highest regarded residency education programs in the United States. It spends over $660 million a year on research and has more than 3,000 full-time research personnel.William Worrall Mayo settled his family in Rochester in 1864 and opened a sole proprietorship medical practice that evolved under his sons, Will and Charlie Mayo, along with practice partners Drs. Stinchfield, Graham, Plummer, Millet, Judd, and Balfour, into Mayo Clinic. Today, in addition to its flagship hospital in Rochester, Mayo Clinic has major campuses in Arizona and Florida. The Mayo Clinic Health System also operates affiliated facilities throughout Minnesota, Wisconsin, and Iowa.Mayo Clinic is ranked number 1 in the United States for 2019-20 U.S. News & World Report Best Hospitals Honor Roll, maintaining a position at or near the top for more than 27 years. It has been on the list of "100 Best Companies to Work For" published by Fortune magazine for fourteen consecutive years, and has continued to achieve this ranking through 2017. Drawing in patients from around the globe, Mayo Clinic performs near the highest number of transplants in the country, including both solid organ and hematologic transplantation.