How many Irish immigrants were there in the South before the war? Precise figures are elusive. But, there are hints. The Irish were generally referred in the immigration records as having come from Great Britain. Arrivals generally peaked in the Spring or Fall, so as to avoid the Summer heat. In the last quarter of 1845, there were 813 arrivals from Great Britain in the port of New Orleans. In late 1846, there were 1,519 arrivals from Britain in New Orleans. In the last quarter of 1847, known as “Black ‘47” – the worst year of the famine in Ireland, there were 3,621 arrivals from Great Britain. During the normally slow summer time, there were 5,856 arrivals from Great Britain in New Orleans.
In 1849, there were 7,272 passengers disembarking at New Orleans. By 1850, New Orleans was second only to New York for Irish arrivals.
In the 1840’s, Liverpool was the center of the cotton trade in Europe. On the return trip to America, the cotton ships would bring immigrants. The cheapest fare to the US was to New Orleans. So, it is not surprising that by 1850, there were some 24,000 Irish immigrants in Louisiana and some 28,000 by 1860. New Orleans had some 116,000 people in 1850 and 168,000 in 1860.
David T. Gleeson, The Irish in the South, 1815-1877 (Chapel Hill, N.C.: Univ. of North Carolina Press 1995), p. 26-27