First there is the matter of the name. Americans typically call them improperly the Scotch Irish. Scotch is the alcoholic beverage; the people are the Scots. Then if a noun is used as an adjective it should be in its singular form. Thus the proper term is Scot Irish. In Britain the term used for these people is Ulster Scots.

First a little ethnic history of Scotland: After the Celtic invasion of Britain about 500 BCE what is now Scotland was occupied and controlled by the Celtic people known as the Picts. This name came from the Latin word pictus meaning painted. They decorated their bodies with dyes.

In the fifth century CE the Scots from northern Ireland invaded what is now western Scotland and established a kingdom in the highlands. They spoke Gaelic, a Celtic language.

At this same time the Anglo-Saxon invasion of Britain was taking place. Scotland consists of the highlands and the lowlands, The Gaelic name for the lowlands is a' Ghalldachd, meaning "the place of the foreigners". And whom might those foreigners be? The Anglo-Saxon invasion of Britain consisted of the Angles. the Saxons and the Jutes. The Jutes came from what is now northwestern Denmark. They settled in the southernmost edge of Britain. The Saxons came from the northwest coast of Germany and they settled in the southern third of Britain. The Angles came from southwestern Denmark and they occupied what are now northern England and the lowlands of Scotland. They were the foreigners referred to in the Gaelic name for the Lowlands.

The language of the Angles evolved into a sister language of the English of Saxons. It is called Lowlands Scots and seems to be just a quaint dialect of English but it has no linguistic relationship to Gaelic, the language of the highland Scots.

In the 17th century the British leaders decided to settle Protestants in the Northern Ireland province of Ulster. They chose to use the Presbyterians of Lowland Scotland. This migration started about 1605.

When the British colonization of North American began many of the Scot Irish chose to join this migration. They were encouraged to settle on the frontier where they could protect the more settled areas from the Amerindians.

By the time of the American Revolution it was estimated that one sixth of the population was Scot Irish. At the time of the Revolution it was said that one third of the population was in favor of revolution, one third was against it and one third was indifferent. All of the Scot Irish were in favor of the revolution and so they constituted 50% of the support for the Revolution.

To see that the Scot Irish were in no way ethnically Scottish or Irish one has only to look at their surnames. For example, take Andrew Jackson, one of the Scot Irish American presidents. One could hardly find a surname more English (Anglish) than Jackson. Or, take Jefferson Davis, the Scot Irish president of the Confederate States of America. Again, Davis is thoroughly English, or one might say more accurately, Anglish because although the country and language were named after the Angles they are the work of the Saxon immigrants.