My group has a few shows coming up. I have several questions about the role of a manager or agent for my a cappella group. I'd like to sing in an a cappella group in my area. There are also choral ensembles at almost every college. Contact the music department for a full listing of choral organizations on campus.
Many schools have music departments with a variety of vocal ensembles.
If you can't find what you're looking for, consider starting a group - remember the King's Singers were started that way 25 years ago. There are barbershop choruses in almost every metropolitan are in the US and many major countries abroad, and you don't need a lot of experience to join. You may have better luck starting your own group than waiting to join one in your area. It's much easier to join a chorus than to find a small ensemble to join. Be sure to find out what will be expected before you join.