This is a common question which comes up here. I would point you toward these responses by /u/sowser which do the topic plenty of justice:

• https://www.reddit.com/r/AskHistorians/comments/4d5c88/were_irish_ever_brought_to_north_america_as_slaves/d1nzkoq
• https://www.reddit.com/r/AskHistorians/comments/40h2rr/was_owning_slaves_in_the_us_limited_solely_to/cyuasd4
• https://www.reddit.com/r/AskHistorians/comments/30l9a9/how_valid_is_the_claim_that_there_were_white/cpth8cw?context=3
• https://www.reddit.com/r/AskHistorians/comments/44a46l/are_there_any_records_of_white_people_being/czozur6