You're right there are a lot of catholic, hispanic immigrants in recent years but a lot of the catholics are there because they live on land that was conquered from the Mexican Empire.
Next to this, and this can apply in many countries, is the cultural-religiosity. Folks who hold on to faiths for their unifying factors, they don't believe but do like it as a means to a social end (getting together, joined participations and such).
(couldn't help sharing this, faiths fascinate me, and i'm like an enthusiastic amateur in delving into these things).
im the only black person i know in New Hampshire