Irish - American families in the 20th century

We leave for Ireland in two weeks and I'm updating the American Brennan tree to show my cousins in Ireland.  I'm searching the recently released 1940 census records as well as new databases that have shown up on ancestry in the past year (when I have mostly been busy finishing my husband's paternal family history book - which is now at the printers).

Sometimes in genealogy, you find something interesting, something you actually hadn't given any thought to, such as how circumstances in the nation might affect the marriage rate and numbers of children and grandchildren in a given family.  Recently I found some interesting data along those lines regarding my family.

My great great grandparents, Ned and Mary, came here in 1861 and had six children, five of whom married and had large families.  Mary Ann, their oldest, had 9 children.  Michael, the oldest boy, also had 9 children.  Bridget had 5.  Edward had 7, and my great grandfather John had 8.  Only Sarah remained single.  But the next generation held a different story.  Some of the children of Ned and Mary had fewer grandchildren than children. Granted, some of the records are hard to find, but one thing stands out: many of the male grandchildren of Ned and Mary never married, and a number of the female grandchildren didn't marry until they were in their forties. There was at least one nun and one priest in this group, so they obviously didn't have children, but many of the others were childless as well.

We're talking about people who were born between the late 1800s and the early 1900s. The youngest of the bunch, one of my great uncles, was born in 1917. 

So I began to ask myself why this was so. Why did so many never marry or marry so late?  And one of the clues came in the draft card registrations for the men.  While most of the young men had a job in 1918 when they registered for the WW I draft, they often listed themselves as unemployed on their WW II draft cards.  I assume this must have been because of the depression, which lasted from 1929 up until WW II.  These men, having no income, must have not been good marriage prospects.  Even if they wanted to marry, they had no means to support a wife and children.  I imagine a good number of them were depressed or despondent over this situation as well, making them poor company to women.  On the women's part, it may not have been easy to find a man with a good income.  Hence, many of them either remained at home, found employment in another town or state, and married in their forties and never had children.

It made me stop and think how the economic situation of the country can affect more than just income levels.  It can actually slow down the rates of marriage and the numbers of children born.  An it can leave a lot of people without the lifelong companionship of a spouse - which I find very sad.