Senate Treaty Documents (Y 1.1/4): Treaties as submitted to the Senate Foreign Relations Committee. These are the best U.S. source if treaties are unratified or not published in TIAS or UST. They may include an article-by-article analysis in the transmittal letters.
Senate Executive Reports (Y 1.1/6): Reports from the committee, with analysis, amendments and reservations, but usually not the complete treaty text. They may include an article-by-article analysis or a summary of select articles. Nominations are also published as Senate Executive Reports.
Senate Treaty Documents and Executive Reports are available in PDF on FDsys with Congressional Documents and Congressional Reports.
International Legal Materials (KZ64 .I58): Available online in Hein Online, Westlaw, Lexis, and JSTOR. Includes major U.S. treaties within a few months of signing, treaty action updates, and draft treaties. ILM also publishes US and other national court decisions on international law, decisions of international courts, and other significant international documents.
The State Department Treaty Affairs site includes a list of pending treaties before the Senate, TIAS treaties listed by year (1996-2015), and a search feature for the Treaty Affairs resources.
Senate Foreign Relations Committee
Senate Treaties page: Current Congress actions includes lists of treaties received, approved, reported, other actions.