1880 US census:
Name: O.A. Dahle
Birth Year: abt 1840
Home in 1880: Winona, Montgomery, Mississippi
Relation to Head of House: Self (Head)
Marital Status: Widower
Father's Birthplace: Norway
O.A. Dahle 40
What source are you using for Ole's birth month and birth year?
I assume this is your Ole at findagrave, but it has his birth year as 1843:http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=DA...
Son Albert O. Dahl's 1952 death certificate. Father: Oleo; mother: Anna.http://tinyurl.com/arvdtju
I have found that the Norwegian name Engebret/Ingebrigt etc. was often Anglicized to "Albert" in the US.
Also, I agree with "Thoraway," that the patronymic name, Amerson/Amersen, is non-existent in Norway! More likely a spelling variation of Amundson/Ammonsen, etc.?