You don't change the infrastructure of a continent that easy. and .. the U.S. was way out front in putting electric power technology to practical use. In the early days, lower voltages were the most practical for electric lights — higher voltages burned out the bulbs. So the hundreds of power plants built in the U.S. prior to 1900 adopted 110 volts (or 115 or 120 volts) as their de facto standard. Starting in Germany around the turn of the century, people adopted the 220-volt (or 230- or 240-volt) standard, mostly because it's easier to transport this way and they had the technology to build better bulbs at the time.