According to the 1841 Census, County Donegal had a population of 296,000 people. As a result of famine and emigration, the population had reduced by 41,000 by 1851 and further reduced by 18,000 by 1861. By the time of the 1951 Census the population was only 44% of what it had been in 1841. The 2006 Census, undertaken by the State's Central Statistics Office, had County Donegal's population standing at 147,264. According to the 2011 Census, the county's population had grown to 161,137.
The variant of the Irish language spoken in Donegal shares many traits with Scottish Gaelic. The Irish spoken in the Donegal Gaeltacht (Irish-speaking area) is of the Ulster dialect, while Inishowen (parts of which only became English-speaking in the early 20th century) used the East Ulster dialect. Ulster Scots is often spoken in both the Finn Valley and The Laggan district of East Donegal. Donegal Irish has a strong influence on learnt Irish across Ulster.