A paper in the 1997 Clogher Record  has an excellent overview of chain migration from Tyrone and Monaghan to the city of Providence, Rhode Island. The author, Edward McCarron, outlines that “between 1825 and 1865, at least 475 persons from county Tyrone and Monaghan were recorded living in Providence and nearby Pawtucket, Rhode Island. The largest contingent, 148 or 37%, came from the parish of Clogher, with significant numbers hailing from adjacent parishes of Errigal Keerogue and Errigal Truagh, straddling the border of Tyrone and Monaghan.”
These numbers are based on an analysis of naturalization records for the city, of which many give an Irish place of origin. More broadly, fully 53% of Irish people who naturalized in Providence between 1840 and 1860 were from Ulster counties - Tyrone, Monaghan, Antrim, Cavan, Fermanagh, Donegal, Down, Derry/Londonderry, and Armagh (listed in order of percentage of overall total).
McCarron outlines a number of different reasons for this chain migration, two of which were economic decline in south Ulster in the 1820s and 1830s and cheaper tickets to Canada with the aim of crossing the border into the New England states. This 19th century migration had a long-lasting effect, and people from the Clogher Valley were “still trickling into Providence in the 1920s, over one-hundred years after the first Tyrone immigrant was recorded there.”
An analysis such as this is an outstanding example of how local history knowledge in Ireland can be combined with a study of particular record sets in the U.S., to create clear evidence of migration from one part of Ireland to one city in America.
 This is the journal of the Clogher Historical Society. Their research focuses on the diocese of Clogher, which consists of Monaghan, much of Fermanagh, and parts of Tyrone and Donegal.
 McCarron, Edward T. Altered States: Tyrone Migration to Providence, Rhode Island During the Nineteenth Century. Clogher Record. Vol. 16. No. 1. 1997. pp. 145-161.