In Classic TWS or Mosaic add the symbol “US-T” in the Financial Instrument field to open the Treasuries contract selection window. You can also add the "Treasuries" icon to the Classic TWS menu line. In the menu line click on the white arrowhead to see a choice to add buttons then scroll through the list and select Treasuries. Once that button is added click on the icon to open the Treasuries contract selection window.
In TWS Mosaic we also have predefined watchists such as U.S. Treasuries (On-the-run) and U.S. Treasuries (All except STRIPs). More information on predefined watchists can be found in the TWS Users' Guide.
You can also use our web based bond search tool to locate all US Treasuries via the "US Treasuries" tab.