Electricians still refer to it as "110" and "220" even though the North American standard has been 120 and 240 volts since at least the 1970s, or around the time they switched from cycles per second to Hertz.
Go back further than that, and nobody could seem to agree on the voltage -- you'll see equipment rated at 110, 115, 117.5, 120, 125, 127, or even 130 volts. Also, the 60 Hz/cps line frequency wasn't standardized until the late 1950s -- before then, there were areas using 25 or 50 Hz. In fact, part of the reason why New Orleans flooded during Katrina was that they were still using old pumps designed for 25 Hz power, and the equipment converting the power from 60 Hz to 25 Hz to run them had failed.