 The Great Famine of the 1840s caused the deaths of one million Irish people and over a million more emigrated to escape it . By the end of the decade , half of all immigration to the United States was from Ireland . The period of civil unrest that followed until the end of the 19th century is referred to as the Land War . Mass emigration became deeply entrenched and the population continued to decline until the mid @-@ 20th century . Immediately prior to the famine the population was recorded as 8 @.@ 2 million by the 1841 census . The population has never returned to this level since . The population continued to fall until 1961 and it was not until the 2006 census that the last county of Ireland ( County Leitrim ) to record a rise in population since 1841 did so . 
 The Great Famine of the 1840s caused the deaths of one million Irish people and over a million more emigrated to escape it . By the end of the decade , half of all immigration to the United States was from Ireland . The period of civil unrest <a href='null_relcl' title='1'><mark>that</mark></a>followed until the end of the 19th century is referred to as the Land War . Mass emigration became deeply entrenched and the population continued to decline until the mid @-@ 20th century . Immediately prior to the famine the population was recorded as 8 @.@ 2 million by the 1841 census . The population <a href='been_done' title='2'><mark>has</mark></a> never returned to <a href='None' title='3'><mark>this</mark></a><a href='negative_concord' title='4'><mark>level</mark></a> since . The population continued to fall until 1961 and it <a href='negative_concord' title='5'><mark>was</mark></a> <a href='negative_concord' title='6'><mark>not</mark></a>until <a href='None' title='7'><mark>the</mark></a>2006 <a href='negative_concord' title='8'><mark>census</mark></a> that the last county of Ireland ( County Leitrim ) to record a rise in population since 1841 did so . 
The Great Famine of the 1840s caused da deaths of one million Irish people and over a million more emigrated to escape it . By tdaend of the decade , half of alll immigration to thdanited States was from Ireland . The period of civil unrest followed until the end of thedath century is referred to as the Land War . Mass emigration became deeply entrenched and the population continued to decline till the da @-@ 20th century . Immediately prior to the famine the population was recorded as 8 @.@ 2 million by the 1da census . The podaation done never returned to no level since . The population continued to fall until 1961 and it ain't util2006 no census that the lasdaounty of Ireland ( County Leitrim ) to record a rise in population since 1841 did so .