Enrolments from American Great Lakes ports are available on microfilm from the US National Archives. A thorough abstract of the enrolments can be found at the Wisconsin Maritime Museum hosted Gerald C. Metzler Great Lakes Vessel Database at http://www.greatlakesvessels.org.
A set of transcriptions of some of the pre-1860 Great Lakes enrolments (including most of those surviving enrolments of steamboats) can be searched at: http://www.maritimehistoryofthegreatlakes.ca/enrolment/default.htm
Merchant Vessels of the United States
An annual printed ship list has appeared since 1867 under the title Merchant Vessels of the United States. The following is a list of those volumes that are online. Note the year in the listing ends on June 30th. The links that follow are all to copies at the HathiTrust. Many of these can also be found at Google Books and the Internet Archive.