The glottal stop is used in American English, yes, but not in the same
places, necessarily, as for British English. It's used (for some
speakers) just before the final unreleased "t" when "t" is final after
a vowel.
"That's it!" (The final "t" is rendered by a glottal stop and/or an unreleased "t" in AmE.)
Some people in the more easterly parts of the U.S. use the glottal stop
for "t" in words like "catalog", but this is not at all common.
The IPA symbol looks something like a question mark as I recall.
CJ