"Population in the US was less than 1/3 the size it is now, then."
So? The population grew dramatically between 1789 and 1913, and the United States *still* became a serious world power without a federal income tax.
"What are you going to do with all the people who paid into Medicare & Social Security their entire lives? Take away their checks? These are pay as you go services."
I'd immediately empty the SS fund by paying back the paid amount to as many people as possible, with a first-in, first-to-get-your-money-back arrangement. When the fund runs dry, the SSA gets relegated to its rightful place atop the ash heap of history. As for Medicare, same thing. I'd freeze all new spending and collections, and reimburse (i.e. un-steal) the money using the same method. Medicaid at the federal level would simply end. Welfare and food stamps would disappear too.
The federal social safety net is grossly unconstitutional, and if it were up to me, I'd dismantle it in its entirety and with extreme prejudice.
The United States of America is simply a loose alliance of 50 semi-sovereign nation-states who unite to conduct business when it is beneficial to all parties, such as when we are attacked. It's despicable to think that a Texan should have to pay a single hard-earned dollar to educate a Californian, or a citizen of South Carolina have to pay to care for a New Yorker. The federal income tax is legalized highway robbery.