The following persons were listed on the 1870 US Census for Mascoutah PO, St. Clair co., Illinois Series: M593 Roll: 279 Page:95 (actual document page: 21)
SPAETH, Faust 43,m, w, hotel & bar room keeper, real estate value: $700Personal: $300, bp: Badenchecked column for male citizen over21 SPAETH, Adelheit, 42,f,w,keepg house, bp: Baden SPAETH, Daniel, 17,m,w, miller, bp: MO (Missouri) SPAETH, John, 12,m,w, at home, bp:Ill (Illinois) SPAETH, Conrad, 10,m,w, at home bp:Ill SPAETH, Henry, 2,m,w, at home bp:Ill
census taken on 11 July 1870
In reviewing this data, one can assume that Faust and his wife have been in the US since at least 1853 and had lived previously in the State of Missouri. St. Clair county, Illinois is across the Mississippi River from St. Louis, Missouri, so in backtracking Faust's travels that is a likely place to research.