Emigration of Lorentz and Bendigte Strand

My great great grandparents came from Norway in about 1872-1873 to either Canada or USA and ended up in Benson, Minnesota. I can not find them on passenger ships to the US so I am thinking they came through Canada. What would be their route and what port would they have landed? I am also trying to find out where in Norway they are from. Any other ways to do this?