Between 1940 and 1979, Chicago experienced a period of industrial dominance, social upheaval, and urban transformation. During World War II, the city alone produced more steel annually than the United Kingdom and, by 1943, outpaced Nazi Germany. This industrial might attracted hundreds of thousands of African Americans from the South in the second wave of the Great Migration, many working in steel mills, railroads, and shipping yards.

In December 1942, the University of Chicago became the site of a historic scientific breakthrough when physicist Enrico Fermi conducted the world’s first controlled nuclear reaction as part of the Manhattan Project, paving the way for the atomic bomb.

Political life was dominated by machine politics under Mayor Richard J. Daley, elected in 1955. His tenure saw significant urban development, including the annexation of land for O’Hare Airport, the construction of the Sears Tower (now Willis Tower), McCormick Place, and the University of Illinois at Chicago. However, Daley’s era also coincided with “white flight,” discriminatory housing practices such as redlining, and blockbusting that reshaped the city’s neighborhoods and racial composition.

The 1960s brought social activism and unrest. Martin Luther King Jr. and Albert Raby led the Chicago Freedom Movement in 1966, achieving agreements with the city to address racial inequality in housing and education. In 1968, the Democratic National Convention became a flashpoint for anti-war protests, with violent clashes between demonstrators and police drawing national attention.

Amid these challenges, the city made cultural strides. Public art flourished, exemplified by the 1967 installation of the Chicago Picasso, which inspired a new era of urban artistic expression. By the late 1970s, Chicago elected its first female mayor, Jane Byrne, who tackled crime in Cabrini-Green and helped stabilize the city’s school system.

This period of mid-century Chicago highlights a city grappling with rapid industrialization, demographic shifts, civil rights struggles, and ambitious urban development, laying the foundation for the Chicago of today.