19th Century Emigration to the North Americas
When measuring the level of emigration it can be difficult, if not impossible, to say with certainty exactly how many people left Ireland during the nineteenth century. No record was taken of those leaving the country. One way to calculate the number of people who left Ireland over the course of the nineteenth century is to start with the number of population in 1801, add the expected growth rate (arrived at by subtracting the number of deaths from the number of births in a year) and any difference between the actual amount in 1901 and what was calculated, is the amount of emigration.
It has been estimated that at the start of the nineteenth century, Ireland had a population of 5.4 million. This swelled to 8.2 million in 1841 - based on a census taken four years before the Famine. In 1851, the number of people recorded as living in Ireland was 6.6 million - in other words, almost two million people had either died or emigrated. Fifty years later, Ireland's population was still showing a decline (down to 4.5 million) even though every other European country was showing a population increase. These figures tend to suggest that approximately 8 million people left Ireland between 1801 and 1900. So how do we know how many went to Canada and the United States?
Most 'guestimates' have been taken from the American and Canadian censuses, which recorded the number of people of Irish birth living there at that time. This is not a very reliable indicator, however, as some Irish people may have been there either on business or on holiday. Others, who originally intended to settle overseas, may have returned to Ireland at a later date. Those who died before being recorded in the census, those who died en route, or those who left Ireland, intending to go to the North Americas but who only got as far as England or Scotland do not appear in these statistics. Passenger lists, which were compiled at the port of entry, not the port of departure, take no account of those who entered at a Canadian port with the intention of going on to America (or, less likely, vice versa).