America's second skyscraper city in numbers, Chicago has an unmatched history of architectural and engineering innovation. In the 1880s and early 1890s, Chicago architects used steel skeleton construction to raise buildings of 16 to 22 stories. During the real estate boom of these years, the midwestern city surpassed New York in the height and number of tall buildings.

In 1893 concerns about overbuilding prompted city officials to enact a height restriction of 130 feet, or around 10 to 12 stories. While the cap was raised and lowered several times between 200 and 260 feet, the tallest Chicago structures were restricted to around 23 or 24 stories. The Jumbos erected from 1900 to 1920 were palazzo-like boxes, impressing people by their bulk, rather than by height.

In 1923 the City passed a zoning law that allowing towers of limited volume. Still, the single Jumbo of the period from 1920 to 1950 was the Field Building, and no Chicago building exceeded 50 stories until 1969.

In the 1960s, a strong economy and the boss politics of Mayor Richard Daley warmed the climate for development, and the skyline surged upward. Chicago architects and engineers again led in new aesthetic and structural approaches to high-rise design. One central influence was the elegant minimalism of Mies van der Rohe and his modernist prisms of steel and glass.

Another key influence was the innovations in structural frames, especially as advanced by the Skidmore, Owings and Merrill partners engineer Fazlur Khan and architect Bruce Graham. Their Jumbo John Hancock Building and Super Jumbo Sears Tower were the most ostentatious demonstrations of new structural systems that offered alternatives to the bay-type arrangement of moment frames, the conventional grid of skeleton construction. In "Big John" they developed a trussed-tube structure that tapered as it rose to 100 stories and displayed its diagonal bracing system on its facade. For the Super Jumbo Sears Tower they employed a bundled-tube structure of nine of squares, of which two rose to the full height of 110 stories.

These boom years also saw the design and construction of the swooping curve of the 60-story National City Bank and the sheer 80-story rise of the Standard Oil / Amoco Building, both Jumbos. The most recent Chicago Jumbos are Water Tower Place and 900 North Michigan Avenue.