Katherine S. Newman in The New York Times:
Debates over the fairness of the tax code are as old as the federal income tax itself. A cornerstone of the tax — established a century ago, by the 16th Amendment — has been the principle that those who make more should pay more, while lower tax rates help the poor to support their families and depend less on government benefits.
That social compact shifted into high gear during the Nixon administration, which tried to incentivize work by rewarding low-income households with a tax break that became the nation’s most successful antipoverty tool ever: the earned-income tax credit. Politicians of both parties have embraced the credit, making it more progressive three times since it was enacted in 1975.
While the federal government has largely stuck by the principle of progressive taxation, the states have gone their own ways: tax policy is particularly regressive in the South and West, and more progressive in the Northeast and Midwest. When it comes to state and local taxation, we are not one nation under God. In 2008, the difference between a working mother in Mississippi and one in Vermont — each with two dependent children, poverty-level wages and identical spending patterns — was $2,300.