I am looking for any help on where to find inforamtion relating to my gggrandfather, Patrick Merrigan. All i have is when he immigrated to Philadelphia from Ireland. I don't have where he came from in Ireland and its like trying to find a needle in a haystack. Are there any records out there (like US Census Records, etc) that can lead me in the right direction? Here is the info on Patrick Merrigan is anyone is wondering. Thanks.

He was born in Ireland between 1830 and 1835 (most likeley in 1833) and married Ann around 1860 before coming to the US in 1861. They had 9 children, but I only have a listing for 8.

Children of PATRICK Merrigan and ANN
2. i. WILLIAM, b: abt 1860.
3. ii. MARY, b: abt 1862.
4. iii. THERESSA, b: abt 1865.
5. iv. EDWARD F., b: Nov 1867; d: btw 1920-1930.
6. v. ANNIE, b: abt 1869.
7. vi. ROBERT, b: abt 1872.
8. vii. KATE, b: abt 1876.
9. viii. JOHN LAWRENCE, b: May 17, 1880.