I'm not a holly expert but I would say yes it's an American, and a spiny one at that.

Naturally the leaves are opposite. Huh? I think you meant alternate.

It certainly looks more like American holly than Chinese or Japanese.

Alternate yes! My lord. Tree id is my weak point but usually I get that one right.

I concur with opinions posted thus far - and I'd say it is definitely Ilex opaca.

Additionally - let's see the other/bigger/older hollies you have; might just be able to ID them for you, too.

Here are some pictures of my bigger Hollies from March of last year. I think opinions were split between Ilex cornuta but leaning towards Nellie Stevens.

Sam said"Your female holly is blooming now and has green stems, it has no I. opaca blood in it.
Try searching your state's botanical garden website and compare to Nellie Stevens. NS is self-fruiting, did your tree bloom last year, did it make fruit?
If not you may have one of several cornuta hybrids."

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