Robert Carlson, Denmark to Michigan

Hello.I am looking for information on the family of Robert Carlson (Rasmus Carlsen) born 1860 in Copenhagen, Denmark and died 1944 in Muskegon, Michigan.He married Christiana Rasmussen also born in Copenhagen in 1865 and died 1915.Don't know either's ancestors.Their children are:

W.R. (Vieko) Carlson born 1878 died 1935 in Muskegon married Annie Sullivan
Alfred (Alford) born 1884 died 1951 married Ella Tank
Olga died before 1935 married Peter Christianson
Anna born 1881 died 1967 married Clinton Claypool
Lawrence married Mary Nelson
Emma married John Hodgson
Martha married W.H. Frost