Trogstad, Christian Haagense(o)n

I have been trying to obtain information for this individual, who is my Great Grandfather for more years than I thought would occur. There are a lot of Trogstads in South Dakota, some whom I've been in contact with and they are the descendents of the brother in the subject. I do not know if they have been successful in discovery anything that they could about these to men. Two brothers are said to have come from Nannestad, Norway in 1865. Christian Haagenson Trogstad was born August 24, 1847 and his death occurred in 1918 in America I believe. He was married to Mina Luella Mickelson, born June 2, 1860. Her death occurred 1898 also occurring in America, I believe. I have a count of nine children, my grandfather one of them. I believe they were all born in America, but the first (I think the first) is born in 1877. The name is Clara Josephine Trogstad. I am looking for the connection of port in the United States and Norway, and anything else possible.