[4][5][note 2] Her thesis was about Quebec City's St. Patrick's Church,[2][5] and her interest in Irish-Quebecer history would continue for her whole life.
[1][4] In 1973, O'Gallagher was allowed by the federal government (who had owned it since the establishment of the quarantine station) to visit Grosse Isle, which she found in a state of disrepair.
O'Gallagher spent the rest of her life writing books and articles on Irish-Canadian history, for which she became a major figure in the Canadian Irish studies community.
[14] She was repeatedly included in Irish America's Global 100 lists,[9][15] and was a member of the organizing committee for Quebec City's 2008 400th anniversary celebrations.
A few months earlier, she had been Grand Marshal to Quebec City's first Saint Patrick's Days parade in 80 years,[1][17] and she was at the time amongst the people featured in the exposition Being Irish O'Quebec at Montreal's McCord Museum.