All this must be viewed in the perspective of the era, not by the child welfare criteria of today. Emigration provided hope, the possibility of a better life, so sacrifices were made. Until c1900 living conditions – by today’s standards – for the majority were appalling and mortality rates for all were high. For example, average male & female life expectancy at birth from 1870 to 1900 was quite constant at just under 50 years for both.*
Social class, urban/rural divide and land tenure also played an important role in emigration. . In rural areas the extended family was the norm, with elderly grandparent(s) sharing the home or living close nearby, so any child would be less ‘lost’ having had a close bond with grandparents since birth. Economic factors could have meant leaving a child behind, as fares increased considerably after the US introduced the Passenger Acts. (Introduced post-Famine primarily to reduce on-board deaths, as sea travel in steerage was a risky business.)
It was very common for part of the family to leave first, usually with the older children who could earn a wage when they landed, allowing money to be sent ‘home’ to bring out others. Many Irish children rarely attended school and when they did it was very part-time – their work contribution was required by the family for survival. This continued until the Irish Education Act of 1892 which made primary education free and mandatory for students between the ages of six and fourteen. Under the early Land Acts tenants benefitted; under the later Acts the labourers got a look-in. Many now had the possibility of an inheritance, rather than being a tenant at will, or one for (usually) three lives.
Emigration of the breadwinner is less common today, but it was frequent and very common in Ireland. Even as recently as 10 years ago after the crash many families were absent one parent; before that in the 1980’s many had to leave for work, and pre-Ryanair a trip home was an expensive affair.
Sad yes, but unusual/infrequent not very.
*There was a slow increase in life expectancy during the early decades of the 1900’s and a ‘jump’ in the 1930’s and 1940’s, due to a variety of factors – discovery and widespread use of penicillin-based drugs, increased spending on welfare, e.g. the introduction of children’s allowances in the 194o's, and the general upgrading of the health services also in the 1940s.