William Buckley Peck Jr. (October 11, 1870 - August 20, 1941) was a prominent physician and surgeon who founded, and for 25 years, served as the managing director of the Inter-State Postgraduate Medical Association of North America, became widely known locally and internationally because of his efforts in continuing education of medical professionals by leading groups of physicians to seminars at European centers of advanced medicine through the Association.

In 1916 Peck organized what was then known as the Tri-State Medical Society when a small group of area physicians met at the Freeport Country club.

At the next society meeting held in the Masonic Temple in Freeport, as many as 400 physicians were in attendance from Illinois, Iowa and Wisconsin.

[5] Peck then recognized that there was a need for an organization that could offer service through keeping medical professionals abreast of the advances in western medicine, many of which were coming from Europe at that time.

Peck's duties as managing director of the association,[2] accompanied by his wife, often took members to all the leading medical centers in Europe and South America.