In researching the Ancestry.com passport records, I found the following quite interesting one for a Rokishoker as follows:
Abel ADELSOHN, born September 1, 1842. Left Hamburg on the Germania on May 1 1886. He lived in Garden City, Kansas. He was naturalized before the District Court in Kansas on July 24, 1891. He was a merchant. He also lived in Denver, CO.
If you look at the Rokiskis vital records, you won't find Abel's birth record as it occurred earlier than any existing records. However, you will find an Abel ben Motel Adelson who had a daughter Feyge Dine on April 11, 1874. Other Rokiskis records connect Abel with his father and siblings.
As you can see, there is quite a bit of info on this passport including a physical description which I didn't include. It is well worth looking through these records in case your relatives can be found there.
Ann
annrab@.....net