A hearty Happy 100th Birthday to the graduated income tax, one of the greatest laws in American history. The 16th Amendment was ratified on February 3, 1913. I wrote about the history of the graduated income tax in detail here.
Also, it’s worth noting that in a lot of debates about presidents, people credit Woodrow Wilson with this because it happened in 1913. But Wilson had nothing to do with it–he hadn’t even taken office yet when it was ratified. Moreover, even if presidents had taken office on January 20 like today, he still would have had absolutely nothing to do with it. If you want to credit a president for the 16th Amendment, it has to be Taft.