Chain migration is the phenomenon when an immigrant already in American wrote home to bring out another. That immigrant in turn induced another to come out, and so on. Strong patterns of "chains" of emigration in some parts of Ireland resulted in Irish county settlements in the U.S. as follows:
Philadelphia PA; Boston MA; Brooklyn NY; NYC west side below 14th Street; Perry County OH
Philadelphia PA; NYC Westside below 14th Street; Springfield MA (Irish speakers from Dingle peninsula); Perry County OH
Hartford, Norwich, Connecticut Valley area, and Waterbury CT; Boston, Holyoke, Chicopee and Worcester MA; NYC's old fourth ward (near today's Manhattan end of the Brooklyn Bridge), Harlem and the South Bronx; Detroit MI; Chicago IL; San Francisco CA
Butte and Anaconda MT; Boston, Lowell, Lawrence, Fall River MA; Bridgeport and Connecticut Valley area CT; South Brooklyn and the north shore of Staten Island NY; Jersey City NJ; NYC's old 7th ward (where the Manhattan Bridge cuts into Manhattan; Detroit MI; San Francisco CA
Providence R.I.; New Haven, Bridgeport CT; NYC north of 14th Street; Morrow County OR
Boston MA; Philadelphia, Scranton and Pittsburgh PA; Jersey City, Newark and Orange NJ; Cleveland OH; Mackinac Island MI; Chicago IL; NYC north of 14th Street
Boston MA; Scranton PA
Boston MA; Philadelphia and Pittsburgh PA (in the "Point" neighborhood; Jersey City, Newark and Orange NJ; Cincinnati OH; Louisville KY; Chicago IL
Providence RI; Newark NJ; NYC (near 14th Street in an area called "Mackrelville"); Perry County OH; Butte and Anaconda MT
Boston MA; Providence RI; Jersey City, Newark and Orange NJ
NYC (especially Brooklyn)
NYC's old 21st ward (between Fourth Avenue and the East River)
Yonkers NY
Philadelphia PA; Greenpoint section of Brooklyn NY; NYC below 14th Street; Perry County OH; Detroit MI
Providence RI; Philadelphia PA; NYC (near Grand Street)
NYC's old "Gas House District" (on the East side north of 14th Street); Detroit MI; Chicago IL
NYC (north of the Gas House District all the way to 59th Street); Detroit MI
Boston MA; NYC (West Village south of 14th Street, close to the Hudson River)
Providence RI
Providence RI
Philadelphia and Pittsburgh PA; Chicago IL
Philadelphia PA
New York City NY; Chicago IL
New York City NY
NYC north of 14th Street
New York City NY
New York City NY
Chicago IL
Michigan's Upper Peninsula; Virginia City NV; Cripple Creek and Aspen CO; Park City UT; Wood River ID; Butte and Anaconda M
The Irish experience has had a profound impact on Connecticut's past, and its narrative spans all periods of the state's history and touches every one of its eight counties and 169 towns.