Following from the previous post, I remembered my copy of Wayland F Dunaway's The Scotch-Irish of Colonial Pennsylvania, first published in 1944. It's an excellent book and in many ways it bridges the gap between the upsurge of Scotch-Irish publishing in the late 1800s and early 1900s, and the later wave in the 1980s and 1990s up to the present day. It has a huge bibliography, a treasure trove of sources.
One of the sources is The History of Bucks County, Pennsylvania, by William W H Davis (1905). It is now available online here. The third volume in the set has numerous usages of the term 'Ulster Scot'. For example:
• GENERAL WILLIAM WATTS HART DAVIS, a veteran of two wars, author, journalist and historian, was born at Davisville, Southampton township, Bucks county, Pennsylvania, July 27, 1820 ... he was either a native of the north of Ireland, or a son of an Ulster Scot, who had made his way to Pennsylvania with the great army of Scotch Covenanters from the province of Ulster in the first quarter of the eighteenth century.
• PROFESSOR A. J. MORRISON, one of the best known educators in Philadelphia, was born in Northampton township, Bucks county, Pennsylvania February 14, 1844 ... John Morrison, the great-grandfather of Professor Morrison, was a native of the north of Ireland, and was one of the great army of Ulster Scots who, having fled from religious persecution and internecine strife in their native Scotia, took temporary refuge in the province of Ulster, Ireland, from whence many emigrated to Pennsylvania in the first half of the eighteenth century.
• CYRUS T. VANARTSDALEN. of Newtown township. Bucks county, was born in Northampton township. April 5. 1823. He is a son of Isaac and Ann (Torbert) Vanartsdalen, the former a descendant through seven generations in an unbroken line from as many Dutch ancestors who emigrated from Holland ... the latter's ancestry traces back to at least four Ulster Scots who found homes in Bucks county a century later.
• JOHN HART, president of the Doylestown Trust Company, and his brother Frank Hart, of Doylestown, retired banker, are the sons of Josiah and Sarah (Brock) Hart. The former was born in Doylestown township, February 3, 1846... On the paternal side they are of Scotch-Irish descent. Among the thousands of Ulster Scots who migrated to Pennsylvania in the first half of the eighteenth century were those who formed two distinct settlements within the present limits of Bucks county...
Yet again, the term 'Ulster Scot'is proven to have a far greater pedigree than many think.