Brad Hubbard, age 15, of  Davenport, Iowa, for his question:

WHEN DID THE MAYO CLINIC START?

Dr. William Worrall Mayo and his sons, William James and Charles Horace, started the clinic in 1889. The name Mayo Clinic dates from about 1903.

Rochester, Minn., is home to the Mayo Clinic, one of the world's largest medical centers. There, a staff of more than 500 physicians care for patients through an integrated group practice of medicine.

Another 750 or so younger physicians assist the staff as part of their residency training in medical and surgical specialties. Just before World War I, the Mayo brothers turned the clinic into a general medical center. Now about 225,000 patients are seen each year with more than 3 million patients having been cared for since the medical center's doors first opened.