Where tech is concerned, your laptop or tablet, smartphone and portable charger, these will all work in the US and you can charge them using a US wall plug. There are two types of US wall plug, 2 pin and grounded 3 pin. I’ve found that the 3 pin wall plug is much more stable, particularly if you’re trying to charge a laptop with the charging block and plug in one.
This UK to grounded US wall plug and extender cable is much lighter than you’d expect, and is extremely useful if you have two items you want to charge/plug in at the same time.
Both single UK and EU plugs will happily plug in to these and you’ll find the wall connection so much more stable than the usual 2 pin adapter. Take a 2 pin with you, as sometimes you’ll just be offered a 2 pin wall option, but much of the time you’ll find that the 3 pin works perfectly Order this for your arrival in the US or have it shipped to you in the UK. A pain I know but these are soooo much better.
This one you’ll need to either order from Amazon in the US, or ship it to yourself in the UK, or preferably have it shipped to wherever you’ll be first staying in the US. With 3 USB ports plus a US plug and a grounded wall connection this clever gadget rotates. It’ll let you plug 3 in USB cables directly and it won’t fall out of the wall so you’ll have a good connection.
Another obvious essential is a portable travel charger for when you're on the move - and not travelling by car - this one by Belkin comes in three levels of power. Be aware that it may be attractive to buy the most powerful but the more power you go for the heavier your battery will be. I take a 5K portable charger with me everywhere.
The 10K and 15K version of this Belkin portable charger also have dual USB ports.
Finally a split charging cable which will allow you to charge up your phone whichever make you have with lightening, micro usb and type C usb connectors.
One reminder - make sure when you're on the move that whatever you've plugged into the wall gets to go with you .......