TRAIL Metrics


TRAIL statistics are updated every six months, generally in January and July.  Some statistics reported below are for the most recent six months, while others are cumulative.

The statistics below are current as of March 17, 2024.

Cumulative Statistics

Number of TRAIL reports available in the HathiTrust Digital Library


Number of TRAIL items available in the University of North Texas Digital Library


Total Reports/Items in Repositories


Total Reports/Items Available



Statistics for the most recent six-month period (July - December 2023)

Number of technical reports processed for digitization


Usage of TRAIL content held at the University of North Texas


Number of TRAIL search interface sessions


Number of TRAIL search interface users



Current Statistics (as of January 1, 2024)

Number of TRAIL institutional members


Number of TRAIL personal members




Number of reports processed

The number of reports that have been processed and counted in one of TRAIL's repositories. Processed reports may not be publicly available.


Total Reports/Items Available    
The combined number of reports (from each TRAIL repository) that are available for public view.


Usage of UNT-located TRAIL content

The number of uses of the TRAIL items stored in the University of North Texas (UNT) Digital Library.  It is not yet technically possible to provide similar usage statistics for the TRAIL content stored in the HathiTrust Digital Library, TRAIL’s other digitization/preservation partner.


Number of TRAIL search interface sessions

The number of times individual IP/browser combinations accessed the TRAIL search interface for up to 30 minutes.


Number of TRAIL search interface users

The number of individual IP/browser combinations that access the TRAIL search interface.

TRAIL - Technical Report Archive and Image Library - logo

Search U.S. government technical reports issued primarily prior to 1976 and digitized by TRAIL.