PURL Enhancement and Stabilization

Since March 1998, the U.S. Government Printing Office (GPO) has used persistent uniform resource locators (PURLs) to provide libraries and other parties stable URLs to online Federal information. GPO's PURL implementation is utilized by Federal depository libraries, Federal agencies, and others to provide persistent links to Federal resources.

In August 2009, GPO's PURL server experienced a significant hardware failure and was unavailable for an extended period. When this happened, all PURL links became inaccessible. The PURL system is a critical tool of the Federal Depository Library Program that fulfills its mission of providing permanent public access to Federal information resources. As a result of the outage, GPO took steps to ensure high availability and redundancy of the PURL application.

Rearchitecture of PURL Software and Hardware

In order to ensure high availability and redundancy, GPO migrated from the original OCLC PURL Resolver Software to the PURLZ Resolver Software, which is a re-architecture of the original OCLC PURL Resolver Software. Included with the migration is the implementation of an improved hosting solution that provides higher availability for the PURL application. Previously, (ro)bot traffic severely hindered the performance of the PURL application and prevented GPO staff from being able to access the system and add/modify PURLs. Under the new hosting solution, the public's and GPO's access is ensured, while still allowing access to traffic, which mostly consisted of link validators.

New PURL Web Address

A new URL of purl.fdlp.gov has been established due to the sunsetting of GPO Access. This new URL ties PURLs to the Federal Depository Library Program. As a result:

  • All new PURLs will use the purl.fdlp.gov address.
  • Direct requests to purl.fdlp.gov will go to a splash page. The domain is used to resolve to Federal resources.
  • All of the 125,000 PURLs that were created using the original OCLC PURL Resolver Software will continue to resolve. No changes will need to be made (at this time) to the existing records that have been made by Federal depository libraries or GPO.

Automated and Enhanced PURL Referral Reporting

As a follow-up from the November 2009 modification of the PURL referral definition and reporting system, an automated PURL referral reporting system was launched on December 1, 2010 that allows Federal depository libraries to view their institution's referrals by individual hostnames and/or IP addresses. The tool also provides a listing of the top fifty (50) referred PURL resources per hostname and/or IP address with:

  • The PURL path.
  • The full path of the target URL for each PURL.
  • The total requests for that individual PURL.
  • A search link utilizing the CGP to view cataloging records for the individual PURL.

GPO still releases monthly PURL referral reports; however, these reports include aggregate totals only. Referrals totals strip out bot traffic and focuses on patron requests.

The PURL Referral Reporting Tool is locked down to Federal depository libraries only. Data is current as of the previous day. Historical data is available for twelve months. Tool functionality may be expanded in the future to include greater historical data retention and additional functionality based on funding and community feedback.

Application Monitoring

The PURL application features high availability and failover services. Traffic routing has been optimized to permit PURL resolution as well as search engines and link checkers.

Learn how Federal depository libraries can utilize PURLs at their institution, more about how PURLs operate, and information on the PURL referral reporting tool, by reading Linking to Federal Resources Using Persistent Uniform Resource Locators (PURLs).

News & Events

October 27, 2021
Today, the U.S. Government Publishing Office (GPO) is performing scheduled maintenance on the FDLP eXchange. Start Date: Wednesday, October... Read More ...
October 26, 2021
GPO staff have made significant headway in the processing and distribution of backlogged FDLP material. Please share these updates... Read More ...
October 26, 2021
How is your library getting in the Halloween spirit this year? Are you featuring any ghoulish Government publications, either online... Read More ...
October 25, 2021
The U.S. Government Publishing Office (GPO) is seeking User Support Librarians to join the Library Services & Content Management... Read More ...
October 25, 2021
The Catalog of U.S. Government Publications (CGP) and MetaLib will undergo maintenance from Monday, October 25, 2021, at 6:00 p.m.... Read More ...
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On October 22, 1965, President Lyndon B. Johnson signed the Highway Beautification Act, which attempted to limit billboards and other forms of outdoor advertising, as well as junkyards and other unsightly roadside messes, along America’s interstate highways. The act also encouraged “scenic enhancement” by funding local efforts to clean up and landscape the green spaces on either side of the roadways. Check out these resources from the CGP:


On October 27, 1858, future President Theodore Roosevelt is born in New York City. He served in the New York state legislature from 1881 to 1884, as U.S. Civil Service commissioner from 1885 to 1889 in Washington, D.C., and then as New York City’s police commissioner from 1895 to 1897. President William McKinley chose Roosevelt as assistant secretary of the Navy later that year. The Republican Party nominated him to be William McKinley’s vice-presidential running mate in 1900. Roosevelt began the first of his two terms in the White House after President McKinley was shot by an assassin in 1901. Check out these resources from the CGP:


Introducing the U.S. Congressional Serial Set collection on govinfo! The initial release includes select volumes from the 69th Congress, the 82nd Congress, and several 19th century Congresses.


Jane Sanchez previously served GPO as its Director of Library Services and Content Management. Prior to her passing in early 2021, she worked as the Law Librarian of Congress and spearheaded the effort to digitize the Congressional Serial Set. The staff at GPO is grateful to Jane for her many contributions to the FDLP.

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GPO names the Government Publications Library at the University of Minnesota Twin Cities as the 2021 Federal Depository Library of the Year. Learn more.


Chris Brown, Professor and Reference Librarian, has been serving as Coordinator for Government Documents at the University of Denver since 1998. He served on Depository Library Council from 2012-2015, with his primary goal being to get vendors with library discovery tools to feature Government information more prominently. He recently published Mastering United States Government Information: Sources and Services (Libraries Unlimited, 2020).

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