What are Ulster Scots?
However, the Anglo-Irish elite based in Dublin required these Presbyterians to tithe to the (Anglican) Church of Ireland, refused to recognize Presbyterian marriages and baptisms, and limited their right to vote. While not treated as harshly as the Irish Catholics, the Scots-Irish were very disaffected by this discrimination. Large numbers of them emigrated to the United States, and are the most important population element in Appalachia and other areas such as the Ohio Valley and the Ozarks. They are an important element in Texas and Oklahoma as well.
They are a population distinct from both the Irish Catholics of the Northeast and Upper Midwest and the mostly English settlers of the Deep South and the Puritan descendants of greater New England.
The Ulster Scots were folks from Scotland planted in what is now Northern Ireland by King James I after 1600. This part of Ireland was the last part to be subdued by England. The Irish chieftains boogied to the Continent and the best land was given to these Presbyterian (and Anglican as well) settlers. The native Gaelic speaking Catholics were driven to the hills. In the 1730s 1740's and beyond thousands of these Presbyterians from Ulster (that provicne in Ireland) came to Ameica because the Presbyterian church wasn't favored either by the English. These people settled what is the frontier PA (beyond Philly),N. Carolina, western Virginia, some of upstate NY, and especially what became Kentuck & Tennessee. They were fiercely independent and joined george Washington's army in droves. This is just an overview---probably a lot you can find.
Wallace T. and brooklyn dave have given you good answers, but as the proud son of Ulster-Scots settlers in Ohio, I can give you a little more.
Before they were "planted" in Ulster to pacify and displace the native Irish Catholics, these people came from the borderlands of Northern England and lowland/southern Scotland, which has always been a very troublesome and ungovernable region.
These "Borderers" or "Reivers" had a tradition of raiding other clans for livestock, women and other booty. As a result, they have a long history of family feuds, reflected in the unpleasantness between the Hatfield and McCoy families (both of whom were of the same stock.) Their culture by necessity inculcated a skill with horse, sword, and gun that may explain their later prominence in military service.
In religion, they were strong anti-Papists and anti-establishmentarians. They subscribed to the Scottish Covenant of the 1600's, which gave rise to the Presbyterian Church and influenced other Dissenters and Reformers such as the Methodists.
By eviction, subsidy, and persuasion, they were settled in Northern Ireland in the late 1600's and 1700's. There, from the point of view of the English King and his bishops, they would be less of a threat to the Crown and established Church of England, and a bulwark against the even worse Irish Catholics.
They were mostly tenant farmers under the thumb of the Anglican nobility, including my own people, who labored on the estate of Lord Montjoy in Omagh. They proved to be as stubborn and warlike in Ulster as they did in the Border Country, thus suffering significant repression at the hands of the Crown and Church, and so in the second half of the 1700's and first half of the 1800's, great numbers of them emigrated to the US.
However, when they arrived, they found some of the same discrimination they had left behind in Ulster. The Anglicans of the South and the Puritans of the North wanted little to do with them. The settlers had to continue on to the backwoods and frontiers to find the liberty they so fiercely craved. From western Pennsylvania, to Ohio, Kentucky, Tennessee, West Virginia, and so on down the Appalachians to northern Georgia and the uplands of the Carolinas, they became the majority. Their Calvinist Presbyterian faith evolved, and many became Methodists, Baptists, or Pentecostals and remain so to the present day.
Their culture survives in the folkways of the Appalachian hillbillies, and much of what is now perceived as Southern speech and manners would be recognizable to an archaic Border reiver of 1600 or so. Most notably, there is a very high premium placed on a man's honor and reputation, and a very low threshold for violent defense of that honor.
Great numbers fought on both side in the Civil War, and the culture gave rise both to eloquent abolitionists and vicious racists. In the Deep South, they were seldom wealthy plantation owners, and more often among the poor white "crackers" and "rednecks". These words reflect their Scottish heritage: "cracker" probably comes from the Gaelic word "craic", meaning bantering, bragging, and boisterous conversation, while "redneck" refers to the Scotch Covenanters who signed the Covenant in their own blood and subsequently wore bloody rags on their necks to signify that fact.
If you find this stuff interesting and wish to learn more about the Scots-Irish, you should look up a book called "Albion's Seed", by David Hackett Fischer. Webb's book is supposed to be good too, but I haven't read it yet.
Ulster Scots are Scots that emigrated to northern Ireland during the 1600’s at the invitation or order of King James.
He had driven a lot of Irish off their land in Northern Ireland (or Ulster as it was called) and wanted to give it to Protestant Scots and Englishmen. The Scottish emigrants were lowlanders, or part of the ruling class. The Highlanders, or commoners, were not invited to emigrate but they emigrated later uninvited. In the 1700’s these Scotch-Irish, as they were called, were persecuted by both the Catholics in Ireland and the Anglicans in England (the Scots were Presbyterians). A famine in Ireland plus other problems in the mid 1700’s caused large numbers of Ulster
Scots to emigrate to the colonies. King George III encouraged this with land grants. The Scotch-Irish came in mostly through the port of Charleston, SC and settled in the Carolinas, Virginia, and the Appalachian regions.
They were more than eager to fight the English in the Revolutionary War, and one officer said that these Scots were among General Washington’s best soldiers. The reason I know all of this is because I am a descendant of an Ulster Scot who left County Antrim and arrived in Charleston in 1763 with his wife and children. One of his sons was a revolutionary soldier.