People crossed out on passenger lists missed the sailing. They didn't
arrive in the US on that ship at all but usually took another ship at
a slightly later time.
"Sometimes (as in the case of my great-grandmother), the immigrants
arrives in New York, but had some medical or financial issue, and were
crossed off the list. The crossed out entries have been micofilmed but
not indexed. My family ended up going to relatives in Canada, and
eventually entered the U.S. by train through St. Albans"