WaPo: Total Number of Tax Breaks in 2011

Washington Post, Building the U.S. Tax Code, Break by Break:

The U.S. government gives away more than $1 trillion a year in tax breaks — subsidies for individuals and companies that are often substitutes for direct government spending. Once written into the tax code, they tend to stick around.

This chart shows the 172 tax breaks currently on the books and the year
each one was first reported by the U.S. Treasury: