Soren Jespersens relatives in Chicago, Cook County

Hi I am looking for Soren Jespersens possible decendents in Cook County, Chicago, Illinois. Here is what i know. Soren Jespersen, born 1855, in Bergen Norway, emigrated to Chicago in 1882. Married (unknown year) a Lina or Lena Miller or Muller and they had two children, one girl born 06 apr 1888, named Bergitte Marie and one boy born 17 aug 1889, named Johan. I cannot find any further trace of the two children, maybe some in this forum can help? Any information will be of great value for me.