Irish music sessions in the USA do in fact take place in pubs or bars, and quite a few bars or pubs do present Irish music. Others present what can very loosely be called folk, but it is really country or acoustic pop. Still others present blues, but it is almost always urban Chicago style blues rather than the old Delta or Piedmont styles.

Most of the folkie scene in the USA (folk revivalists, tradition-based contemporary singer-songwriters, not-so-tradition-based contempoarysinger-songwriters, topical and political singer-songwriters, etc.) is based in coffee houses, house concerts, festivals, and the programs presented by folk music societies, which are rather different from UK folk clubs. For example, many folk music societies in the USA organize weekend getaways as part of their program.

There are also parallel "folk scenes" in the USA for various non-Anglophonic ethnic folk music communities, including Balkan, Hungarian, Scandinavian, and Latin American, among others. I am not very familiar with what goes on among them.