In addition to searching the Trademark Search database, a thorough clearance search should also include:
View the most recent issues of the Trademark Official Gazette here. It is published each Tuesday and contains bibliographic information and a representative drawing for each mark published, along with a list of cancelled and renewed registrations. Archived issues from 2001 - 2020 can be viewed here.
Trademark Status and Document Retrieval (TSDR)
From the TSDR page, the user can access the complete electronic record for all U.S. trademark applications, registrations, and Madrid Protocol applications filed through the USPTO and corresponding International Registrations by entering a U.S. application serial number, U.S. registration number, U.S. Reference Number, Expungement/Reexamination Petition or Proceeding Number, or International Registration Number, as appropriate. If you do not have this information, you can find it by searching the mark through Trademark Search (uspto.gov).
Use the "Status" tab to find the official record for the mark, including the mark information, goods/services, filing basis information, current owner information, attorney/correspondence information, prosecution history, and current location of the application.
Use the "Documents" tab to find copies of all incoming correspondence, all outgoing Office actions and notices, search summaries, notes to the file, processing snap shots and the initial application.