03/17/1962
https://www.presidency.ucsb.edu...
"Well, let me be a little more precise. Do you think appreciation of assets that are not sold, unrealized gain, should be taxed?"
"Should someone, should any American have to pay tax on unrealized gain, or can't you just answer me?"
"What do you think Dr. McBride? Do you think we should start taxing unrealized gain, and what do you think that will do to the economy?"
"I can show you study after study after study, as you well know, and as the professor knows. It shows that people are leaving high tax states and moving to low tax states."