My Waack came from the same area.Now I have noticed it says Rostock, Mecklinburg-Schwerin. Gustav Waack (b1834-d1908 Ida Grove, Iowa) came with his wife Dorathea Paap Waack (b1834-d 1913 Ida Grove, Iowa). They brought over Sophia b1863 and Frank b1867. I have found family from Sophia. I am from Franks family. They had more children. From the list of birth dates they were here by 1869, Emma was born here in Chicago.
Looks like we have to find family in Germany! We have to be connected some how. This is not a common name.