Chicago is the most populous city in Illinois and the Midwest, and the third-most populous in the United States with a population of over 2.7 million as of 2020. It is the county seat of Cook County, the second-most populous county in the U.S., and the center of the Chicago metropolitan area (Chicagoland), home to 9.6 million residents.
Around 1900, the period from the Great Chicago Fire had a lasting influence on American literature.
In 1900, over 77% of Chicago's population was either foreign-born or born in the United States of foreign parentage.
In 1900, the city completed a major engineering feat, reversing the flow of the Chicago River to flow away from Lake Michigan, resolving sewage contamination issues.
In 1901, William Rainey Harper established Joliet Junior College as the first junior college in the nation.
Since 1901, the White Sox have continuously played on the South Side.
In 1905, donors such as Benjamin Ferguson established funding for public art.
In 1906, the Chicago Cubs and the Chicago White Sox faced each other in a World Series.
In 1907, the Brass Era car builder Bugmobile was founded in Chicago.
In 1908, the Cubs began the longest championship drought in American professional sports, which lasted until 2016.
Between 1910 and 1920, Chicago's black population doubled due to an influx of African Americans from the American South.
Between 1910 and 1930, Chicago experienced a dramatic increase in its African American population, growing from 44,103 to 233,903 due to the availability of jobs during World War I and the 1920s.
By 1910, Chicago had become the nation's railroad hub, with over 20 railroads operating passenger service out of six different downtown terminals.
In 1912, Harriet Monroe founded Poetry magazine, which became influential.
In 1919, Chicago experienced racial tensions and violence, including the Chicago race riot.
In 1919, the ratification of the 18th amendment ushered in the beginning of the gangster era in Chicago due to Prohibition.
Between 1851 and 1920, Chicago grew by incorporating neighboring townships, driven by the municipal services the city offered its residents. 1920 marked the end of this period.
Between 1920 and 1930, Chicago's black population doubled again, continuing the influx from the American South.
From 1920 to 1921, Chicago was affected by tenant rent strikes.
From 1920 to 1921, Chicago was affected by a series of tenant rent strikes, leading to the formation of the Chicago Tenants Protective Association and the passage of tenant laws.
In 1924, Chicago saw the formation of the Society for Human Rights, the first American homosexual-rights organization.
Since 1927, the citizens of Chicago have not elected a Republican mayor.
From 1928 to 1933, the city witnessed a tax revolt, leading to an inability to meet payroll or provide relief efforts.
In 1929, Chicago was the location of the infamous St. Valentine's Day Massacre, where Al Capone's men gunned down members of Bugs Moran's rival gang.
Between 1910 and 1930, Chicago experienced a dramatic increase in its African American population, growing from 44,103 to 233,903 due to the availability of jobs during World War I and the 1920s.
Between 1920 and 1930, Chicago's black population doubled again, continuing the influx from the American South.
By 1930, two-thirds of Chicago's black population lived in sections of the city that were 90% black in racial composition.
By 1931 the Republican political machine in Chicago was utterly destroyed by the economic crisis, and every mayor since has been a Democrat.
By 1933 over 50% of industrial jobs in the city had been lost, and unemployment rates amongst blacks and Mexicans in the city were over 40%.
By 1933, the fiscal crisis was resolved, and federal relief funding began to flow into Chicago.
In 1933, Chicago Mayor Anton Cermak was fatally wounded in Miami, Florida, during a failed assassination attempt on President-elect Franklin D. Roosevelt, and Chicago celebrated its centennial by hosting the Century of Progress International Exposition World's Fair.
The gangster era roughly spans from 1919 until 1933 when Prohibition was repealed.
On July 24, 1934, Chicago recorded its highest official temperature reading of 105 °F (41 °C).
In 1933 and 1934, the city celebrated its centennial by hosting the Century of Progress International Exposition World's Fair.
By 1935 the Workers Alliance of America began organizing the poor, workers, the unemployed.
In the spring of 1937 Republic Steel Works witnessed the Memorial Day massacre of 1937 in the neighborhood of East Side.
During World War II, the city of Chicago alone produced more steel than the United Kingdom every year from 1939 – 1945.
On December 2, 1942, physicist Enrico Fermi conducted the world's first controlled nuclear reaction at the University of Chicago as part of the Manhattan Project.
The building of the boulevard system continued intermittently until 1942.
In 1950, Chicago reached its highest ever recorded population of 3.6 million, according to the census.
A number of Chicago's public art works are by modern figurative artists such as Moore's Large Interior Form, 1953-54.
In 1955, Richard J. Daley, a Democrat, was elected as mayor of Chicago.
In 1956, Chicago conducted its last major expansion when it annexed the land under O'Hare airport.
In 1956, the Lithuanian Opera Company of Chicago was founded by Lithuanian Chicagoans.
In 1966, Martin Luther King Jr. and Albert Raby led the Chicago Freedom Movement.
In 1968, Chicago hosted the tumultuous Democratic National Convention, marked by confrontations between anti-war protesters and police.
In 1968, members of the Chicago Imagists like Roger Brown and Leon Golub produced bizarre representational paintings.
Since 1968, the Joseph Jefferson Awards have been given annually to acknowledge excellence in theater in the Chicago area.
In 1969, members of the Chicago Imagists, continued to produce bizarre representational paintings.
From 1973 to 1975, Robert P. Hanrahan represented a significant portion of Chicago.
In 1974, the Sears Tower (now known as the Willis Tower) became the world's tallest building.
From 1973 to 1975, Robert P. Hanrahan represented a significant portion of Chicago.
Since 1977, the Chicago Marathon has been held each year except for 1987.
In 1979, Jane Byrne was elected as the city's first female mayor.
In 1983, Harold Washington became the first black mayor of Chicago.
On January 20, 1985, Chicago matched its record low temperature of -27 °F (-33 °C).
From 1983-1987, Harold Washington was in office.
In 1987, Harold Washington was re-elected as mayor of Chicago but died of a heart attack soon after.
In 1987, a half marathon was run in place of the Chicago Marathon.
On September 10, 2012, teachers for the Chicago Teachers Union went on strike for the first time since 1987.
In 1989, Richard M. Daley became Chicago's longest-serving mayor.
By the time of the 1990 census, Los Angeles had overtaken Chicago as the United States' second-largest city.
In 1990, Chicago's South Side and the adjoining south suburbs constituted the largest black majority region in the entire United States.
In 1991, Lollapalooza, an annual festival, originated in Chicago and initially traveled to many cities.
In 1992, a construction accident caused a breach connecting the Chicago River to an abandoned freight tunnel system, leading to widespread flooding in the downtown Loop district.
Since 1992, with Chicago's Democratic vote the state of Illinois has been "solid blue" in presidential elections.
The second Parliament of the World's Religions was held in Chicago in 1993.
In 1994, the United States hosted a successful FIFA World Cup with games played at Soldier Field in Chicago.
During the 1995 heatwave, Midway Airport recorded a heat index of 125 °F (52 °C).
From 1995 to 1997, Michael Patrick Flanagan represented a significant portion of Chicago.
From 1995 to 2008, the city had a blue bag program to divert recyclable refuse from landfills.
From 1995 to 1997, Michael Patrick Flanagan represented a significant portion of Chicago.
Since its founding in 1997, the Chicago Fire FC has won one league title and four U.S. Open Cups.
The 2000 census showed a rise in population for Chicago.
As of 2002, severe freight train congestion caused trains to take as long to get through the Chicago region as it took to get there from the West Coast of the country.
In 2003, Robb Report named Chicago the country's "most exceptional dining destination".
In 2005, O'Hare was the world's busiest airport by aircraft movements and the second-busiest by total passenger traffic.
In 2007, a University of Chicago report ranked Chicago third among U.S. metropolitan areas in "size of music industry" and fourth among U.S. cities in "number of concerts and performances".
From 1995 to 2008, the city had a blue bag program to divert recyclable refuse from landfills.
In 2008, Chicago agreed to a 75-year, $1.16 billion deal to lease its parking meter system to Chicago Parking Meters LLC.
Until 2008, the Merchandise Mart had its own zip code.
Since 2009 Chicago relinquished rights to its public street parking.
According to U.S. Department of Transportation, the volume of imported and exported goods transported via rail to, from, or through Chicago is forecast to increase nearly 150 percent between 2010 and 2040.
By 2010, Chicago's population had declined to under 2.7 million.
On February 23, 2011, Rahm Emanuel won the mayoral election in Chicago.
On May 16, 2011, Rahm Emanuel was sworn in as mayor of Chicago.
In winter 2011, Chicago experienced a significant blizzard.
On September 10, 2012, teachers for the Chicago Teachers Union went on strike for the first time since 1987.
From 2012 to 2019, 33 Chicago alderpersons were convicted on corruption charges.
In 2012, Chicago became a "de jure" sanctuary city when Mayor Rahm Emanuel and the City Council passed the Welcoming City Ordinance.
In July 2013, the bicycle-sharing system Divvy was launched with 750 bikes and 75 docking stations.
From 2013 through 2018, Chicago was ranked the nation's top metropolitan area for corporate relocations.
In 2013, over half of Chicago's elected alderpersons took illegal campaign contributions.
In 2013, the Chicago Stars FC joined the National Women's Soccer League (NWSL).
In 2013, the Chicago school district had an enrollment exceeding 400,545 students.
In 2013, the violent crime rate was 910 per 100,000 people, and the murder rate was 10.4 per 100,000 in Chicago.
Since the 2013 legalization of same-sex marriage in Illinois, over 10,000 same-sex couples have wed in Cook County, a majority of them in Chicago.
According to a 2014 study by the Pew Research Center, Christianity is the most prevalently practiced religion in Chicago (71%), making the city the fourth-most religious metropolis in the United States.
According to data compiled in 2014, Chicago's "choice system" sorts students of different achievement levels into different schools.
In 2014 the Catholic Church was the largest individual Christian denomination (34%), with the Roman Catholic Archdiocese of Chicago being the largest Catholic jurisdiction.
In 2014, Non-Christian faiths accounted for 7% of the religious population.
Rush University Medical Center was ranked as the second best hospital in the Chicago metropolitan area by U.S. News & World Report for 2014–16.
In 2015, 26.5 percent of Chicago households were without a car.
In 2015, Rahm Emanuel won re-election as mayor.
In 2015, the steel industry in Chicago employed only 28,000 workers, a significant drop from its peak during the 1960s.
In 2016, the Cubs won the World Series, ending their championship drought.
In 2016, the percentage of Chicago households without a car increased to 27.5 percent.
According to September 2017 estimates, Chicago had the third-largest gross metropolitan product in the United States, about $670.5 billion.
In 2017, Chicago exchanges traded 4.7 billion in derivatives.
In 2017, WYCC 20, Chicago's second PBS member station, removed its affiliation with PBS.
In 2017, a study by Walk Score ranked Chicago as the sixth-most walkable of the fifty largest cities in the United States.
Northwestern Memorial Hospital is ranked as the best hospital in the Chicago metropolitan area by U.S. News & World Report for 2017–18.
As of 2018, Windy City Live is Chicago's only daytime talk show.
From 2013 through 2018, Chicago was ranked the nation's top metropolitan area for corporate relocations.
In 2018, Chicago ranked seventh globally for the highest number of ultra-high-net-worth residents, with roughly 3,300 residents worth more than $30 million.
In 2018, the Chicago Department of Health estimated that 7.5% of the adult population (approximately 146,000 Chicagoans) were LGBTQ.
In 2018, the Chicago Park Boulevard System Historic District was listed on the National Register of Historic Places.
In 2018, the Chicago area's gross domestic product (GDP) was $689 billion.
Beginning in January 2019, Newsy started producing 12 of its 14 hours of live news programming per day from its new facility in Chicago.
In January 2019, a polar vortex event occurred and nearly broke the city's cold record of -27 °F.
In May 2019, The City of Chicago announced its Chicago's Electric Shared Scooter Pilot Program, scheduled to run from June 15 to October 15.
As of July 2019, Divvy operated 5800 bicycles at 608 stations.
During July 2019, a heat wave caused dew point temperatures to reach nearly 80 °F (27 °C).
In July 2019, non-Hispanic Whites made up 32.8% of Chicago's population, Blacks 30.1%, and the Hispanic population 29.0%.
From 2012 to 2019, 33 Chicago alderpersons were convicted on corruption charges.
In 2019, Lori Lightfoot was elected as the city's first African American woman mayor and its first openly LGBTQ mayor.
In 2019, Nexstar Media Group acquired WGN from Tribune Broadcasting, obtaining a majority stake in The CW network.
A 2020 study estimated the total Jewish population of the Chicago metropolitan area at 319,500.
In 2020, Chicago's crime rate was 3,926 per 100,000 people.
The 2020 census showed a rise in population for Chicago.
Chicago's minimum wage for non-tipped employees reached $15 in 2021.
In 2021, Chicago was ranked the fourth-most walkable large city in the United States.
According to U.S. Census Bureau data estimates for 2022, the median household income in Chicago was $70,386, and the per capita income was $45,449.
According to the 2022 American Community Survey, the specific ancestral groups having 10,000 or more persons in Chicago were surveyed.
In 2022, three Fortune 500 companies left Chicago, leaving the city with 35, which was still second to New York City.
Since 2022 have already recouped over $1.5 billion in revenue for Chicago Parking Meters LLC investors.
On May 15, 2023, Brandon Johnson assumed office as the 57th mayor of Chicago.
According to U.S. Department of Transportation, the volume of imported and exported goods transported via rail to, from, or through Chicago is forecast to increase nearly 150 percent between 2010 and 2040.
The rights of the parking ticket lease end in 2081.