Muslims have steadily increased through immigration and conversion of Afro-Americans. Some reckon they may now number nearly 8 million with more than 1,500 mosques. Of special mention:
i) Arabs. Many are Muslim but the majority are Christian. The small minority of Islamists among them have gained notoriety for the community.
ii) Iranians may now number 2 million with 500,000 in California alone. Disillusionment with Islam has caused some to become Christians — Iranian Christian Fellowships are coming into being.
iii) Somalis, Afghans, Bosnians, etc., are all significantly growing refugee communities.
Source: Operation World