It's hard to tell there's a recession on at the nation's medical schools, where business appears to be booming.

Responding to warnings of a looming doctor shortage, existing schools are increasing enrollment, and new ones are opening or under development.

A quarter century ago, experts blamed rising health costs on what they said was a surplus of doctors performing unneeded procedures.

But the president-elect of the American Medical Association, Dr. J. James Rohack, says Americans are living longer and need good doctors.

This year alone, the number of accredited medical schools in the U.S. is set to grow by four to 130.

Health care in America is a $2.4 trillion annual business. President Barack Obama has made overhauling health care an early priority of his administration.

Highlights of doctor demand and medical school enrollment:

—The U.S. will have about 750,000 doctors by 2025, about 159,000 fewer than it needs, according to the Association of American Medical Colleges.

—The U.S. population is expected to increase from 300 million in 2006 to 350 million in 2025, and a larger proportion will be older, thus more likely to need doctor care.

—42,231 people applied to U.S. medical schools in 2008, and 18,036 enrolled.

—Four new medical schools are to accept students this year: Texas Tech University in El Paso, Florida International University in Miami, University of Central Florida in Orlando, and Commonwealth Medical College in Scranton, Pa.

—Five schools are seeking accreditation and aim to begin classes in 2010 or 2011: Virginia Tech in Roanoke; Scripps School of Medicine in La Jolla, Calif.; Oakland University in Royal Oak, Mich.; Touro University in Hasbrouck Heights, N.J.; and Hofstra University in Hempstead, N.Y.