Government technical reports include U.S. government-sponsored research. "These reports are usually prepared by government contractors and grantees (such as universities, research organizations, or corporations) and consist of progress and final reports on projects." Most of these reports are indexed and sold via that National Technical Information Service under the U.S. Department of Commerce.

Other federal agencies such as DOE and NASA offer access to technical reports.

(Source: Using Government Information Sources. Sears and Moody. Oryx, 1994.)

• National Technical Information Service
  The official resource for locating government-sponsored U.S. and worldwide scientific, technical, engineering, and business-related information. Search publications from 1964- . See also this search interface which allows for searching by specific data sets.
• Science.gov
  Searches over 45 databases and over 2000 selected websites from 14 federal agencies. Gateway to authoritative selected science information research and development results.
• National Institute of Standards and Technology (NIST) Publications Portal
  Includes many of the most recent publications of the National Institute of Standards and Technology (NIST). 
• Library of Congress Technical Reports and Standards
  The Technical Reports and Standards Unit (TRS) of the Library of Congress holds one of the largest accessible collections of technical reports and standards in the world: Technical Reports - Over 3 million in microform, digital media and paper .Standards - thousands in paper, microform, CD and online. 
• NASA Technical Report Server
  Over 500,000 aerospace-related citations, over 200,000 full-text online documents, and over 500,000 images and videos are available. NTRS integrates NASA's following three collections and enables search and retrieval through a common interface:
  • NACA Collection: Citations and reports from the National Advisory Committee for Aeronautics period lasting from 1916 to 1958.
  • NASA Collection: Citations and documents created or sponsored by NASA starting in 1958 and continuing to the present.
  • NIX Collection: Citations and images, photos, movies, and videos are downloaded from the NASA Image eXchange and served out through NTRS. NIX is a separate system and users can also go directly to the NIX site to search imagery.
• Technical Report Archive & Image Library (TRAIL)
  Search U.S. Government technical reports prior to 1975.