Chicago
UTC−5United States · CDT
Thu, 13 Aug 2026
Timezone Guide
Chicago, United States runs on UTC−5. Clocks move forward each spring and back each autumn: UTC−6 in winter, UTC−5 in summer. Next change: 1 Nov. There is a 1-hour difference between Chicago and New York. Standard 9-to-6 working hours overlap for about 8 hours a day with New York. A good time to connect: 09:00–17:00 in Chicago lines up with 10:00–18:00 in New York. There is a 6-hour difference between Chicago and London. Standard 9-to-6 working hours overlap for about 3 hours a day with London. A good time to connect: 09:00–12:00 in Chicago lines up with 15:00–18:00 in London. There is a 14-hour difference between Chicago and Tokyo. Standard working hours don't overlap at all with Tokyo, so meetings need an early or late slot on one side. This timezone is also shared with cities such as Bogotá, Lima, Quito. Keeping these offsets in mind makes it easier to schedule calls or travel to and from Chicago.
Practical Info
Chicago (United States) is home to roughly 9.6M people. Today brings about 15.3 hours of daylight: sunrise at 05:12, sunset at 20:30. Clocks move forward each spring and back each autumn: UTC−6 in winter, UTC−5 in summer. Next change: 1 Nov. It sits in the Northern Hemisphere, about 42° north of the equator. Traffic drives on the right.
Flag
United States
Capital
Washington, D.C.
Continent
North America
Time Zone
CDT · America/Chicago
Coordinates
41.88°N, 87.63°W
Currency
USD ($)
Calling Code
+1
Driving Side
Right
Hemisphere
Northern
Language
English
Measurement System
Imperial
Did You Know?
Chicago Made a River Run Backwards and Got Away With It
By the end of the 1800s, Chicago had a problem: its sewage flowed into the Chicago River, the Chicago River flowed into Lake Michigan, and Lake Michigan was the city's drinking water. The city considered its options and concluded that the cleanest solution was to reverse the river.
At dawn on 2 January 1900, a small group of officials broke the final dam. It was done quietly and early, with only a few friendly reporters present, because Missouri was in the middle of suing to stop it and nobody wanted a judge finding out that the job was already finished.
The case reached the U.S. Supreme Court — the first pollution case it ever heard. Chicago won. Justice Oliver Wendell Holmes noted that the Mississippi was indeed foul, but that Chicago could hardly be blamed for all of it, given how many closer cities were doing exactly the same thing.
The river has been running the wrong way for a hundred and twenty-six years.
As a bonus: the famous green dye started as sewage detection. City workers were using dye to trace illegal discharges into the river. In 1962 someone tipped in a hundred pounds of it, the river stayed emerald for a week, and a municipal leak-detection technique became an annual civic celebration.
The clock: Chicago is also where time zones happened.
Before 1883, North America ran on roughly three hundred separate local times, each town setting noon by its own sun. Workable for farming, catastrophic for railways. In October 1883, the railroads met at the Grand Pacific Hotel in Chicago and simply imposed four time zones on an entire continent, without asking a single government.
The switch came on 18 November. The Chicago Tribune's reporter watched the depot clock stop at noon, and be restarted nine minutes and thirty-two seconds later — at noon again. The papers called it the day of two noons.
The hotel is gone. The building on its site is now called the Central Standard Building.
Sources
- Chicago Tribune archives, "In 1883, much of the nation reset its clocks on 'the day of two noons'"
- Library of Congress, "This Month in Business History: The Day of Two Noons"
- WTTW Chicago, "Reversal of the Chicago River"
- Missouri v. Illinois, 180 U.S. 208 (1901)
- WBEZ Curious City
- NPR, on the sewage-detection origin of the green dye (1962, 100 lbs)
Annual Daylight
Working Hours
1h overlap