Ernest August Knorr (1840-1917) lived primarily in Washington DC. On the 1920's census his children indicated he came from Greifenberg. Since all other references were to Prussia or Germany, I conclude that the Greifenberg in question is/was the one in Pomerania (and is now Gryfice, Poland.)
Ernest and August are STRONG family names -- there are at least 4 of them in the DC / Baltimore area and I've got reason to believe (other than the name similarity) they are all related. Two of them are also referred to as Peter / Pete. Other family names that may be relevant: Charles, Julius, Ferdinand, Fred, Amelia (Emilie?).
I find on Genelogy.net a few Knorrs with the names of Ernest and August. There was a Fredrich Ernest Knorr who lived in Pielburg.
These Knorrs were merchants, confectionaries, cigar makers, a doctor, a journalist ...
I'm looking for any hints / clues / musings to help me on my journey ... Thanks