Real number, with all the outsourced debts is well over 100 trillion already. But you can do this as long as other countries believe in your currency and they use it for bigger credits. American dollar is losing it's ground as world reserve currency. Russia and China already have their own financial system, their own cards, and they trade with each other, without US dollar. Same thing is happening with other countries, fully in debt or with extreme inflation (where crypto currencies are being massively used - like Dash in Venezuela...) So, what  USA was doing in last 50 years, was just printing money, and other countries were producing actual goods, and they made a trade. Pretty good and extremely cheap for US, I'd say. But that is all turning around. Slowly but surely. Just look at the average worker. So now when other countries don't want to use US dollar as much as before, US banks (and US citizen) will see real problem. Probably most countries, because central banks all around the world work together. No currency lasted forever. All of them (which are not backed by silver/gold) turn to zero in the end. And same thing is waiting for USD and eventually EUR (and all other currencies around the world). And the reason for that is greed. Nothing else.