The problem is that records are missing. I would suspect that the 6th Louisiana (largely Irish) and the multinational 10th (at least 24 nationalities) might edge out the 9th for most number of men born outside of La. But of the 1,146 men who served in the 6th, only 893 gave a place of birth on the muster book (of these, only 139 were born in Louisiana). And the 10th Louisiana's muster book no longer exists as far as is known. If someone was really curious, they might could go through the regiments' microfilm at the State Archives and check each man's record to see if a place of birth is listed.