Before John Vassos revolutionized the form, the turnstile—traditionally constructed with arms that rotated like the blades of a helicopter—was a ubiquitous but inefficient mechanism for organizing the flow of crowds. By reorienting the arms—a “milk stool on its side,” as he described it—Vassos engineered a faster way to move people through space that with its sleek, modern lines also suggested unhindered movement. First deployed at the 1933 Chicago World’s Fair, Vassos’s Turnstile soon graced some of the nation’s most important entryways—including the lobby of the Empire State Building and New York City’s subway stations—and is still in production today.