Five years later... in the Soren Sorensen family in the 1870 census in Chicago.

We ask what happened to Anne Caroline and notice a new baby Carrie.

1870 census

United States Census, 1870," index and images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M676-PM7 : accessed 23 Feb 2013), Swen Sorenson household, Illinois, United States; citing p. 310, family 2152, NARA microfilm publication M593, FHL microfilm 545705.

Perhaps this interment list will shed some light:

If this Anne M Sorenson that passed away at 1 year 3 months in August 1869 belongs to Anne Margrethe then their second daughter, Anne Caroline, that migrated with them also must have passed away after arriving in America.  It is a fourth daughter, then, that shows up in the 1870 census as Carrie Sorensen born about January 1870.
Also notice, Anne H Sevinson died at age 47 years, 10 months in November 1879.  This matches the age of Anne Margrethe Nielsdatter Sorensen.  So is this person on the interment list the same?  It is in Familysearch as such.
Finally notice the death of Soren Sorenson August 1904, age 77.

Again notice the research that could be done to account for this family in the United States.