Alexander Kelly Belfast Northern Antrim

Can you give an approximate date for his birth, plus his denomination? There’s 35 people named Alexander Kelly in the 1901 census, so it’s a common name. Without a bit more to go on, it wouldn’t really be possible to answer your query.

Alexander Kelly was born May 20, 1760 Belfast Antrim 

1760 is long before the start of birth registration in Ireland (1864) and so you need to rely on church baptism records. You didn’t say what denomination Alexander was but I’ll guess he was either Presbyterian or Church of Ireland.  Few of those records for the 1700s are on-line.  You would need go to PRONI (the public record office) in Belfast to go through the records for the 1700s. I think there are about 5 or 6 churches which would have records for 1760. This link explains what records exist, parish by parish:

https://www.nidirect.gov.uk/publications/proni-guide-church-records

If you are unable to go yourself, you could employ a researcher. Researchers in the PRONI area: http://sgni.net

My ancestor was also Alexander Kelly born May 20, 1760.  Son of Peter Kelly andAnnAdair.

settled in Westmoreland Co, PA. He had two wives an 19 children.   But that’s all I know about him.

 This information is from a history of Western Pennsylvania.  Would love to find out more