Gee, around here (Chicago) it seems most Mexican restaurants serve beef
soup and chicken soup (caldo de res and caldo de pollo). The ones that
serve seafood also usually serve shrimp soup and seafood soup (caldo de
camaron and caldo 7 mares) as well as chicken and beef soups. Menudo
and posole are very common but usually served only on weekends.

-bwg