Tax Foundation, Local Income Taxes: City- and County-Level Income and Wage Taxes Continue to Wane:

Most U.S. cities and counties do not impose a local income tax, but they are imposed by 4,933 jurisdictions in 17 states, encompassing over 23 million Americans. Varying from minute amounts in several states to an average 1.55% in Maryland, these taxes provide a long-standing and significant source of revenue to many cities in “Rust Belt” states in the northeastern United States.

All counties in Indiana and Maryland impose a local income tax. In Ohio, 593 municipalities and 181 school districts have such a tax. 2,469 municipalities and 469 school districts in Pennsylvania impose local income or wage taxes. Many cities and school districts in Iowa and Michigan also have these taxes.