If your immigrant ancestor became a citizen (census records would tell you if he was naturalized), finding his naturalization papers may tell you where he was born. Naturalization records are usually at the local courthouse; some have been indexed (and some are online). Try Ancestry, FamilySearch, state and county archives, county genealogical society, etc. County histories that have family or individual biographies can sometimes give valuable clues or facts as this information was often provided by the families themselves. Larger genealogy libraries often have collections of these. Some have been digitized and are available at various sites, such as archive.org.
You may want to look at the German edition of Ancestry which is available at the Family History Centers.
Try the German genealogy sites, such as gedbas.
Should you narrow it down to a specific town, Archion may be of use (fees will apply). Also look at “Meyers Orts” to get more information about the town.
Have you looked for an “Ortssippenbuch” for the family? If one exists, and you can find it, it can be a goldmine.
