Electricity in the U.S.
There is 110 volts in America. Most electrical devices that you want to bring (e.g. hair dryer, battery charger) will usually switch automatically to 110 volts, or these can be manually switched. If in doubt, consult the manual. If your equipment is not suitable for 110 volts you can buy a 110-220 converter.
Plugs and sockets are different in America. You will have to buy an adapter if you want to use your own electrical devices.
Or you can, after arriving in the U.S. buy a mains plug at e.g. Walmart or Kmart and assemble this plug at the cord of your electrical device.