[2] These were "Yankee" settlers, meaning they were descended from the English Puritans who settled New England during the early 1600s.

They made up virtually all of Winnebago County's inhabitants during the first several decades of its history.

After the conclusion of the Black Hawk War there was an additional surge of immigration from New England.

[16] In terms of ancestry, 25.6% were German, 13.5% were Irish, 9.4% were American, 8.7% were Swedish, 8.3% were English, and 7.4% were Italian.

From the 1850s to 1988, it backed the Republican candidates for president at every election except the national Democratic landslides of 1936 and 1964.

In the 1990s, it became a swing county, backing the national winner in every presidential election from 1992 to 2012, though only three did so with a majority and only once by more than six percentage points.