Carl and Dorothea Ulrich were living in the Willow Creek area by 1870, although they are called "Conrad" and "Dora" in the 1870 census. Their sons Charles and William are living with them.
In the 1880 census they are "Carl" and "Dorothea" and are living with their son Charles' family.
I found what appears to be Carl and Dorothea in the Brandenburg Prussia Emigration Records on Ancestry, showing that the family originated in Wichmannsdorf/Templin and emigrated in 1866.The emigrees are:
Carl Ulrich, born 5 December 1803, Dorothea Ulrich, nee Mohr, born 4 March 1808, Emilie Marie Auguste Ulrich, born 8 May 1844, Bertha Marie Auguste Ulrich, born 12 April 1847, Carl Friedrich Wilhelm Ulrich, born 11 January 1850, and Wilhelm Friedrich August Ulrich, born 27 October 1852.
Are any of these people your ancestors.Please reply to me at firstname.lastname@example.org.