Illinois is surrounded by states that have much higher positivity rates, according to data Friday.
Using the latest public health information provided by states across the country, NBC 5 Investigates looked at Midwest states that border Illinois and compared their positivity rates to the 3.9% Illinois reported Friday.
By comparison, Wisconsin had a positivity rate of 6.9%, Indiana was at 8.9%, Missouri sat at 9.7%, Kentucky was at 5.7% and Iowa was reported to be 8%.
Another Midwest state not bordering Illinois, Michigan, stood at 6.1%.
With the exception of Iowa, each state's positivity rate was calculated using a seven-day rolling average. Iowa, however, only publishes positivity rates for a single day. The state's 8% was reported Thursday.
Several states listed, including Wisconsin, Missouri and Iowa, are also currently on Chicago's travel order, which requires anyone visiting or returning to the city from those states to quarantine for 14 days.
States are added to the list if they have "a case rate greater than 15 new COVID-19 cases per 100,000 resident population, per day, over a 7-day rolling average."
"We're watching all of our neighbors very, very carefully and we're going to be very prudent," Lightfoot said Monday.
So far, Indiana has not been added to the city's list.
""They are in the 10-15 range so we certainly are watching to see what happens," Chicago Department of Public Health Commissioner Dr. Allison Arwady said Tuesday. "I think it's not by accident that if you look in the last week where are we seeing in Chicago some of our highest percent positivity, some of our highest cases, they're down in the zip codes that border Indiana, where we know that right over the border percent positivity is much much higher, number of cases per population is much higher. It's a risk, but we chose that cutoff for a reason and people will go on and off that list when or if they either hit or come off that cutoff."
The move comes as states across the U.S. see surges of coronavirus cases, many shutting down bars and restaurants in an effort to quell or prevent a spike.
New cases have surged in several states across the nation, setting new records, driven mostly by expanding outbreaks in the American South and West.
New York and New Jersey are also asking visitors from several states, including Illinois, to quarantine themselves for two weeks.
Still, outside of Chicago, Illinois Gov. J.B. Pritzker said the state likely won't require residents who travel to and from neighboring states to quarantine for two weeks solely because of that travel.
"We don't live in a country where you close the borders between states," Pritzker said during the governor's coronavirus briefing. "And we're not going to stop people who live in Illinois and work in Wisconsin from doing so."
Illinois' health department has, however, recently blamed travel to neighboring states for recent spikes in some Illinois counties.
Previous warnings issued in Adams and Peoria counties blamed in part travel to hot spots including Wisconsin, Iowa and Missouri for recent outbreaks that led to an increase in metrics.