The Amendments to the 1787 Constitution - The Sixteenth Amendment
Added: February 3, 1913
States in the Union: 48
The reported number is 38 States (79% of the Union) ratified this amendment. This number of States that ratified is questionable, or at least the number of States that followed proper ratification protocol
The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.
You can read the Sixteenth Amendment for yourself, here.