Between all of the M7 Counties (Milwaukee, Kenosha, Ozaukee, Racine, Walworth, Washington, and Waukesha), Milwaukee County is the only one to support a net outflow of personal income, meaning there's more revenue earned in Milwaukee County by non-county residents.
All of this revenue is taxed and those income taxes go to the state, therefore, Milwaukee County is a large reason why surrounding counties are able to send more.
This is on top of the fact that Milwaukee County is already the largest contributor to the state every year in terms of income and sales tax, despite receiving either a flat or declining amount of state aid in return.
Given these circumstances, this makes a strong case for Milwaukee County to acquire a new, unique revenue source.
To learn more, visit: https://county.milwaukee.gov/