Marginal Tax Rates, Arnold Kling | EconLog | Library of Economics and Liberty
A very good point from Arnold Kling.
And a related point frrom Greg Mankiw:
http://gregmankiw.blogspot.com/2009/11/poverty-trap.html
Pay really close attention to the left-hand side of the chart, boysengurls, not that the trend goes DOWN between $19K and 39K.