Tom Ryan said:To clarify (hopefully): The usual "15 amp style" 110 v. is actually rated to take up to 20 amps. So it is possible to run a 20 amp circuit (with appropriate wiring), terminate it with a "15 amp style" outlet, and use it (legally) for 20 amps. In that case, you can't tell from the outlet whether it is for a 20 amp circuit or a 15 amp circuit. You'll have to go to the circuit breaker box. Around here (central PA) it's hard to get anyone to install a 20 amp style outlet. And the only good reason to do so that I can think of is if you have a Festool Vac and don't like using a dongle.
Tom in Central PA
Many/most new homes around here that do not have central air conditioning have a 20A near a window.