Saturday saw the largest one-day increase, so far, in the number of new coronavirus cases in Illinois and in the areas surrounding Chicago in northwest Indiana, southwest Michigan, and southeast Wisconsin.

NBC 5 Investigates has now tracked 11,025 cases, with 265 deaths.

That includes 1,566 newly-reported cases of coronavirus in Illinois and the regions surrounding greater Chicago, and 37 new fatalities.

Those numbers include the largest single-day increase in most every county in the immediate Chicago area, including the city of Chicago; Cook, DuPage, Kane, Kankakee, Kendall, Will and Winnebago Counties in Illinois; Rock County in Wisconsin; and Lake and St. Joseph Counties in Indiana.

NBC5 Investigates has also discovered an especially steep rise today in the two counties bordering St. Louis, Missouri: St. Clair County, IL, where cases shot up 22% today to a total of 80 cases there; and Madison County, IL, just to the north, where cases shot up more than 51% just today, to a total of 47 cases there.

Boone County – northwest of Chicago – which previouslystayed clear of any coronavirus cases within its county limits – reported its first coronavirus cases Saturday.