The treasury
@hollydolly does not have the money in the way you mean. The USA is deeply in debt. I wish I had more education so I could explain it better. It’s like you run up the full amount on a credit card. Then you get another credit card and get a cash advance on that credit.
With that cash advance, you make payments on the charged up credit card and you buy stuff on the credit. Once that credit card is full, and you are out of money, you get another credit card, get a cash advance, and make payment on both of the other credit cards, and charge more.
Rinse repeat repeat, but credit card money is not “real” money it is virtual money. Just like bit coins are not real money, they are virtual money. Of course, you have a real job, (taxes in the case of the USA).
But you overspend so then you use your credit (in the case of the USA you borrow money from other programs, and other nations) to meet your bills. Individuals have yard sales to get more money. The USA has sales also. Old military equipment, land we own in other countries such as no longer used military bases etc.
In the end, money is just paper. We have lots of trees, which make lots of paper, which makes lots of money. If people spend the money, then more businesses will pay taxes, then the treasury gets more money, etc. until the system overloads as it did in the Great Depression a d we all start over again.