Its been 120VAC in the vast majority of the US since quite some time like the 1940's - 1960's.'
A minority are still 115-120VAC but very few still at 110VAC or even 110VDC.
But 110V line voltage is still too common of a misconception still lingering overseas.
This can be seen in some power transformers which are built overseas with multiple primary windings intended for international use. Often these will step-up or step-down the incoming line voltage to the working level correctly using the 240V primary when 230-240V is actually powering the transformer through that winding. But when used in the USA with the 110V primary, the transformer powers the working circuit with almost 10 percent higher voltage than the engineers thought they were going to get.
A minority are still 115-120VAC but very few still at 110VAC or even 110VDC.
But 110V line voltage is still too common of a misconception still lingering overseas.
This can be seen in some power transformers which are built overseas with multiple primary windings intended for international use. Often these will step-up or step-down the incoming line voltage to the working level correctly using the 240V primary when 230-240V is actually powering the transformer through that winding. But when used in the USA with the 110V primary, the transformer powers the working circuit with almost 10 percent higher voltage than the engineers thought they were going to get.