The North's First Minister, the Rev Ian Paisley, and Deputy First Minister, Martin McGuinness, have begun a week-long visit to the United States with a visit to the New York Stock Exchange, where they received a rapturous reception from Irish-American business leaders.
"I swore I was not going to use the word 'historic' again but it keeps popping into my head," said philanthropist Loretta Brennan Glucksman, chairwoman of the American Ireland Fund. "What a day!"
Dr Paisley and Mr McGuinness arrived amid the flickering screens of the exchange at 8am, an hour before the trading day began, mounting the podium to pose for dozens of cameras below. At a breakfast hosted by Duncan Niederauer, who was starting his first day as chief executive of the stock exchange, Dr Paisley invited all the investors present to visit Northern Ireland for themselves.
"We'll give you more than breakfast," the First Minister said. "But as a strict teetotaller, I will keep the chief executive away from the main distillery in Northern Ireland, which happens to be in my constituency."
For many Americans, the most fascinating element of the two Ministers' appearance yesterday was the ease with which the old adversaries interacted with one another, sharing jokes and taking every opportunity to compliment one another. "I am very proud to work with Ian Paisley, a man who has shown tremendous leadership," Mr McGuinness said.
If Americans were impressed by the historic symbolism of the visit, the visitors themselves were quick to stress their hardnosed purpose in New York.
"We have entered a new era where our key priority is to build economic prosperity - taking all the great assets of Northern Ireland and creating business opportunities that will offer a good return on investment for you and that will benefit our people. We will be carrying the message of profitable business partnerships in all our meetings this week," Dr Paisley said.
US financial services companies such as Allstate and Liberty Mutual are already established in the North and Dr Paisley encouraged other potential investors on Wall Street to talk to those who have experienced the economic opportunities on offer.
"They can tell you, first hand, about the skilled and loyal workforce and highlight the excellent labour relations that exist between the employers and employees," he said.
Later, at City Hall, the two Ministers invited New York mayor Michael Bloomberg to visit the North next year. He agreed, on condition that he could play golf at the Royal County Down Golf Club, which boasts one of the greatest links courses in the world.
Referring to Mr McGuinness, Dr Paisley told Mr Bloomberg of the depth of the political transformation that has taken place in the North. "The divisions of Northern Ireland have been overcome in many ways by an enormous change of thinking. There were places in Belfast I could not walk. There were places in Belfast he could not walk. We can walk everywhere today," he said.