Their names are EXCEEDINGLY common. When were they born? When did they arrive in the U.S.? What was her maiden name?
Look for clues in censuses, death records, obituaries, church records, and so forth. The U.S. Federal Census for 1900 provides a month and year of birth, the number of years a couple has been married, a year of immigration, and more. The 1910-1920-1930 censuses provide a year of immigration. The 1910 census also tells how long a couple has been married. The 1930 census asked how old a person was at "first" marriage.
You need to gather many more clues (or if you have them, tell them to us). There are some fantastic emigration databases and other databases for Swedish research but you have not provided enough information to separate your Adolph from thousands of others also named Samuelsson, and without Anna's maiden name, she can't be separate from many, many, many Annas who emigrated. Women in Sweden back then seldom used their husband's patronymic last name after marriage.