The setup

By 1908, the United States had roughly 150 medical schools teaching a patchwork of approaches side by side: conventional (allopathic) medicine, homeopathy, eclectic (botanical) medicine, naturopathy, osteopathy, and chiropractic — with wildly uneven standards from school to school.

The report

The Carnegie Foundation commissioned Abraham Flexner — an educator, not a physician — to evaluate every medical school in the U.S. and Canada. His 1910 report, Medical Education in the United States and Canada, explicitly modeled “good” medical education on the germ-theory-based biomedical curriculum at Johns Hopkins, and recommended closing schools teaching rival approaches, which he labeled “sects.”

The consequence

Within about a decade, roughly 80% of programs teaching homeopathy, naturopathy, eclectic medicine, and similar approaches had closed or been forced to conform; the overall number of U.S. medical schools roughly halved.

The financial follow-through

Rockefeller philanthropies, separately from Carnegie, then directed large-scale funding specifically toward schools that adopted the biomedical/pharmaceutical model, while schools that didn't conform received none — turning Flexner's recommendations into an enforced, self-reinforcing funding structure rather than just advice on paper.

Why it's the hinge

State licensing boards, hospitals, and insurers converged on the Flexner-approved biomedical model as the legal, professional standard for “medicine” in North America. This is the single event that both cemented germ theory as the official standard and cut off terrain theory's institutional path forward — one report, both consequences.

This account draws on the historical record of the Flexner Report's content and Rockefeller/Carnegie funding patterns that followed it, which is well documented. Framing of intent behind those decisions varies by source; readers should weigh the underlying facts independently.