Hi, I can confirm that the prominent John Lawler of Prairie du Chien (the railwayman) was born in Rathvilly, Co Carlow in 1832. A Jerome Lalor (b 1813) lived in Prairie du Chien in the 1870s before moving onto Independence, Iowa. His parents were Patrick Lalor & Anne Dillon of Tenakill (near Mountrath). I have quite a bit on the Lawlers of Queens County and might be able to place your family with a bit more information.
John Cherry