There are 2 separate indexes for Baltimore for the years 1833-1866. One lists passengers on federal lists, the second lists passengers on city lists. You can't just check one - if you check one and don't find your ancestor, you have to
check the other one.
For a list of Film Numbers for Ships to Maryland, after 1820, see
For online Ships to Maryland see
If you want to search multiple websites at once for passenger lists, there is a custom search engine for Ships going to Maryland at