Buncrana, Co Donegal, is the most Catholic town in the Republic, with 94.3 per cent of its population belonging to the denomination.
Greystones, Co Wicklow, has the highest Church of Ireland (including Protestants) population, at 11.3 per cent.
Some Church of Ireland members do not consider themselves to be Protestant.
In official "religion" figures from the April 28th, 2002, census released by the Central Statistics Office (CSO) yesterday, other "most Catholic" towns included Ballina, Co Mayo (94.1 per cent), and Carrick-on-Suir, Co Tipperary (93.8). Other "most Church of Ireland (including Protestant)" towns were Wicklow (4.8 per cent) and Bandon, Co Cork ( 4.7 per cent).
The number of people without a religion almost doubled between 1991 (the previous census to include a religion question) and 2002, growing from 66,000 to 138,000.
Almost half of those were aged between 20 and 39, with 60 per cent male.
The number of those in the "not-stated" category when it came to religious affiliation or none dropped from 83,375 to 79,094 in 2002.
This group also had the highest incidence of marriage breakdown of all categories, with almost 20 per cent separated or divorced in 2002. Corresponding rates for Muslims and Catholics were 5 per cent and 9 per cent respectively.
People aged 65 and over accounted for 15 per cent of the Church of Ireland (including Protestant) population, compared to a national average of 11 per cent for that age cohort.
Over 65s accounted for 1 per cent of Muslims in the State, who also accounted for the highest proportion of young people, with 28 per cent aged between 0 and 14. Confirming preliminary figures released last June, the CSO noted dramatic increases in the Muslim and Orthodox populations between 1991 and 2002. The number of Muslims more than quadrupled to 19,000 while the Orthodox population grew from 400 to 10,000.
Other main features of the 2002 census were sizeable increases in population numbers for all the Christian denominations, representing a reversal of the long-term decline in Anglican and Protestant denomination numbers for the first time since the State was founded. There was a similar reversal where the Republic's Jewish population was concerned.
However, though the number of Catholics in the Republic grew by 234,300, or 7 per cent, (to 3,462,600) in 2002, the Church's proportion of the population dropped from 91.6 per cent to 88.4 per cent.
This was accounted for by an overall 11.1 per cent increase in the population between 1991 and 2002.
Significantly, over a third of Muslims (19,147) belong to the three highest social class categories, i.e professional (4,257), managerial and technical (2,243), and non-manual (1,123).
Another 1,950 belong to the skilled manual category.