First found in Ayrshire, where they held a family seat from very early times.

Dalriadan families proliferated in North America. Their descendants still populate many communities in the eastern parts of both the United States and Canada. Some settled in Canada as United Empire Loyalists, in the wake of the American War of Independence. Families on both sides of the border have recovered much of their heritage in the 20th century through clan societies and highland games. Analysis of immigration records indicates that some of the first North American immigrants bore the name McIlwraith or a variant listed above: John McIllreavy landed in Philadelphia, Pennsylvania in 1846; Archibald McIllree landed there in 1832; William McIlrea landed in Philadelphia in 1834.

Motto Translated: By sea and by land.

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