Physical Therapists formed their first professional association in 1921, called the American Women's Physical Therapeutic Association. Led by President Mar McMillan, an executive committee of elected officers governed the Association, which included 274 chapter members. By the end of the 1930s, the Association changed its name to the American Physiotherapy Association. Men were admitted, and membership grew
to just under 1,000.

With the advent of World War II and a nationwide polio epidemic during the 1940s and 1950s, physical therapists were in greater demand then ever before. The Association's membership swelled to 8,000, and the number of physical therapy education programs across the US increased from 16 to 39.

By the late 1940s, the Association had changed its name to the American Physical Therapy Association, hired a full-time staff, and opened its first office in New York City. A House of Delegates representing chapter members was established to set APTA policies. The House elected Board of Directors, previously the Executive Committee, to manage the Association. In addition, Sections were created to promote and develop specific objectives of the profession. The first two Sections were the School and Private Practice sections.

In the 1960s, APTA membership reached almost 15,000, and the number of education programs nationwide grew to 52. Now headquartered in Alexandria, Virginia, APTA represents more than 75,000 members throughout the United States. A national professional organization, APTA's goal is to foster advancements in physical therapy practice, research, and education. Currently 180 institutions offer physical therapy education programs and 236 institutions offer physical therapy assistant education programs in the United States.