Not "narrow" by any stretch. Not as spreading as a Q. alba or macrocarpa. More like a bicolor. Probably slightly taller than wide from what I have seen on mature specimens.

This is a good example.

Don't worry -- it'll gradually spread just like hair's impressive example.

Acer, better check that sapling for girdling roots before you transplant.....

I have visited many champion tree program websites for this same reason. I wanted to see several mature specimens of each oak variety to make sure that I had planted each in the right place in my yard. Most oaks get AT LEAST 60 ft wide, and 50-60 ft in height. MOST get 80 ft or more in width and vary in height from 60-100 +ft in old age. But I will likely never see ANY of my oaks at maturity, you may if you are young enough. Well, I am 43, so I MAY be lucky enough to see some of my oaks get kinda big. Unfortunately, many big/champion trees will say how wide the crown spread is, but only show the trunks in photos on the champion tree sites.

Bottom line - Quercus michauxii is a fine tree - one of my favorite oaks, and not planted often enough.

It doesn't need a "swamp" either - although it's thirster than upland oaks like Scarlet Oak and (regular) Chestnut Oak (Q. prinus), it should do fine in any normal east-coast moisture situation. That said, I'd avoid it in drier areas like Texas, Oklahoma, etc, unless it's sited in a moist area.