The largest county in Missouri by population is st. Louis
Cook County is the largest, by far, containing the City of Chicago. For further info, check out the Encyclopedia Brittanica or Wikipedia.
Aroostook County is a county located in the U.S. state of Maine. In 2000, its population was 73,938. It is the largest county in the state. Its seat is Houlton.[1] In land area, Aroostook County is...
The largest county by population in the US state of Wyoming is Laramie County with a population of 91,738 according to the 2010 US Census.
Marion County has the largest county population in Indiana.