The 16th Amendment to the Constitution was enacted on Feb 13, 1913. Truly, one of the worst days in American history.

In 1909 progressives in Congress again attached a provision for an income tax to a tariff bill. Conservatives, hoping to kill the idea for good, proposed a constitutional amendment enacting such a tax; they believed an amendment would never received ratification by three-fourths of the states. Much to their surprise, the amendment was ratified by one state legislature after another, and on February 25, 1913, with the certification by Secretary of State Philander C. Knox, the 16th amendment took effect. Yet in 1913, due to generous exemptions and deductions, less than 1 percent of the population paid income taxes at the rate of only 1 percent of net income.
http://www.ourdocuments.gov/doc.php?flash=true&doc=57

It must have seemed so innocuous at the time; only 1% are going to pay, and taxing the rich is always a good idea, yeah?

It seems this strategy of daring your opponent to cross a line can have far, far reaching consequences. It remains to be seen how sequestration will play out. We can all hope it plays out better than the bet taken by "conservatives" in 1913.

It would have been promoted during the terms of Teddy Roosevelt and Taft, who, because of their income tax push and their railroad and transportation killing ICC, rank very near the top on my personal list of Presidents I dislike.