From the Transactional Records Access Clearinghouse at Syracuse University:

The latest information about U.S. taxpayer returns is now available on TRAC's web site. New this year is a powerful app that makes it much easier to browse through extensive information on the constantly shifting kinds of income flowing to taxpayers in the fifty states and every one of the more than 3,000 counties.

TRAC's new Taxpayer Returns application can help identify changes in overall income trends, spot unusual contrasts since 1991 and zoom in and focus on particular communities. Built-in ranking information and graphic displays help bring all this information into sharp focus.

The data reported on federal income tax returns — including adjusted gross income, wages and salaries earned, interest income, dividend income, and exemptions claimed — provide unique views of the economic conditions of the country as a whole, as well as for each state and county. At the same time, the tax return information offers unusual insights about the sources of the income flowing from incomes taxes into the federal coffers.

• New York Times, Taxes and Salaries, County by County
• Web CPA, TRAC Report Offers Deeper View of Tax Return Data