Searching for Louis Elster. b. 1866 in Sweden. When did he immigrate to America, when did he marry Minnie, before he immigrated to USA or later on after he arrived?

The US Censi for 1900,1910 and 1920 show the Elster family living on a farm in the Jackson Township of Lee County, Near Keokuk, Iowa. On these records, the Head of Household is identified as Louis Elster, b. 1866 in Sweden. The wife, Minnie, is born in 1868, in Ohio.
I have not been able to locate any immigration information for Louis Elster. I do not not know where Louis and Minnie were married.

I am descended from Ruth Blomquist, who visited four cousins in the Elster home in the early 1900's. I do not know if the cousins are related to Ruth and Esther by their mother's side, or their father's side. I know that their father, John Blomquist.was born as Johannes Felt, in Jonkoping, Sweden to Gustave and Johanna Felt on 9-15-1859. Johannes was one of 12 children.
Request assistance regarding the identity of Louis Elster. Can you find him in Sweden before he immigrated to USA?
All assistance is appreciated. Thanks