Today I found this record at Ancestry:
Sam Newmark - arriving in Quebec on Nov 14, 1903 on the "Parisian" steamship crossed the border at Niagara Falls on November 30th. He was born in the Radom Province of Russia, and his last residence was in England. He was headed towards Rochester, New York to look for work.
While the place of birth isn't very clear on this card (and the Ancestry indexer went with "Edom") the matching manifest clearly says Radom, and Radom is an actual Polish Gubernia, which includes Warsaw, where I believe my Newmark ancestor was born. He's the last entry on the manifest:
From other manifests I know Samuel and his son, Barnet, travelled to the US in 1907, returned to England in 1908, and the whole family made the final voyage in 1909. But if this is my ancestor, it appears Samuel made an earlier voyage in 1903, a few months after his final son, Israel David, was born in April. His eldest, Sol, was married in 1902, and likely was the primary wage earner for the family while these trips were made.
I also note that there is a Morris Stone, also from the Radom Province, also a tailor, and also headed to Rochester. It may be a coincidence, but they may also have been travelling together.