If you're looking for truly historic change, you won't have to go far: try the Irish precincts of Boston, which are steadily depopulating. Once Irish people came to Boston and New York by the thousands, fleeing repression, poverty and lack of opportunity; now many more are going back across the ocean to Ireland.
Kevin Cullen has a remarkable series on this tectonic shift in the Boston Globe(where else?) this week. He cites as key factors in this turnaround the Irish economic boom, which has created thousands and thousands of high-paying jobs and made for an incredibly high standard of living there. There is also a "new normal" for Irish people here illegally: they are being deported now, rather than allowed to stay with a wink and a nod. That seems to be a permanent feature of post-9/11 America.
Incredibly, there are so many ex-American Irish living in the legendary County Kerry, in the southwest corner of Ireland, that some residents have deemed their neighborhood "Little Boston." You can read the yesterday's kickoff story and succeeding parts here.