Thank you.
Strange. If this is compatible with USA law, I wonder, why other USA exchanges do not allow the same limits.
(I guess it is a competitive advantage if an exchange allows higher limits.)
Edit:
Ah I suppose, this is because Poloniex does not allow to trade real USD.
But: I guess there are other USA exchanges, that do not allow to trade real USD, but have nevertheless a smaller limit. So the question of interest remains.
I think this is a generalization of the fiat and crypto withdrawal limits on the amount each exchange can handle (in terms of risk), the US exchanges definitely offer fiat withdrawals as well to some US local banks which may require other reconciliations.