US Income Tax passed into law on Feb 3rd 1913

On February 3, 1913, the Sixteenth Amendment to the United States Constitution was ratified by the United States Congress, allowing the Federal government to collect a tax based on income. While the Constitution give the Congress the power of taxation, a Supreme Court case had held that direct taxes on income were unconstitutional. In 1909 President Taft initially proposed a constitutional amendment and, though passed by the Congress in 1909, the amendment required three full years for ratification.

Here's the 1913 form 1040. I wish it was still this simple!

As often as I been to DC I've never seen the IRS headquarters on any tours. I can only wonder why.