A.D.F. Hamlin's Chicago School was rooted in the untrammeled freedom of art in America and offered bold, utilitarian solutions for early skyscrapers with vertical lines rising uninterrupted from the basement to the roof. Thomas Tallmadge responded to Hamlin, but redefined the term, inspired by the great American planes and their horizontal lines. Sigfried Giedion returned to the initial definition and was followed as well as opposed by many later writers. Meanwhile, William James witnessed the birth of a Chicago School of Thought around John Dewey's pragmatist philosophy. Robert Park became the central figure in a Chicago School of Sociology that explored human nature. And in economics, Milton Friedman crusaded for free markets and free choice. Furthermore, there were Chicago Schools of Fiction, Broadcasting, Advertising, and many more. This present dissertation collected, cataloged, and evaluated everything called Chicago School. Based on this data, it is possible to tell from a collective point of view what successful Chicago Schools were. In addition, Sigfried Giedion's school marks a turning point in history. After Giedion's essay was published, multiple schools of thought rose to fame together. Why did this trend only come into action a century after the first mentions of a Chicago School? To understand this delay, I developed a theory based on the variability of definitions and the responsiveness of audiences. Mathematically, the Theory of Varieties builds on equations previously employed in other disciplines. In the Humanities, it may help evaluate the evolution of cultural trends.