Saint Patrick's Day has been a public holiday in the Republic of Ireland since 1904.
The holiday was established under the Bank Holiday (Ireland) Act 1903, introduced by Irish MP James O'Mara. The legislation created the legal basis for 17 March to become a bank holiday, with the first observance under the new arrangement taking place in 1904.
This distinction explains why 1903 and 1904 are both encountered in historical accounts. 1903 is the year of the act, while 1904 is the year the public holiday came into effect. The date is also a public holiday in Northern Ireland and is observed in many Irish communities worldwide.
The Irish national holiday later developed into a large cultural festival, especially after the establishment of the Saint Patrick's Festival in Dublin in 1996. Public-holiday status, however, concerns employment and official closures rather than the beginning of the religious feast itself.