It stretches “all the way back to the age of Shakespeare, at least”:
“The meaning of the word has changed a lot over the last four centuries,” said Dana Ste. Claire, a Florida historian and anthropologist who studies, er, crackers. … Ste. Claire pointed me to King John, published sometime in the 1590s. One character refers to another as a craker — a common insult for an obnoxious bloviator.
What craker is this same that deafs our ears with this abundance of superfluous breath?
“It’s a beautiful quote, but it was a character trait that was used to describe a group of Celtic immigrants — Scots-Irish people who came to the Americas who were running from political circumstances in the old world,” Ste. Claire said.
Those Scots-Irish folks started settling the Carolinas, and later moved deeper South and into Florida and Georgia. But the disparaging term followed these immigrants, who were thought by local officials to be unruly and ill-mannered. “In official documents, the governor of Florida said, ‘We don’t know what to do with these crackers — we tell them to settle this area and they don’t; we tell them not to settle this area and they do,” Ste. Claire said. “They lived off the land. They were rogues.”
One Scots-Irish view of the matter:
The Dish 