I spent a combined 3 months in the US last year over a couple of different trips and across 3 states. Everywhere took card payments and accepted Monzo, so given that most ATMs over there will charge a fee, my personal advice would be to use card payments as much as possible rather than withdrawing cash all the time.
If you do need to use an ATM, the Mastercard ATM finder is usually pretty handy at finding a nearby one.
Enjoy your trip! 