The CALS Encyclopedia of Arkansas is a project of Central Arkansas Library System (CALS) in Little Rock, Arkansas. It is the only state encyclopedia in the country to be produced by a library system. The CALS Encyclopedia of Arkansas strives to offer a definitive, comprehensive, and accurate record of America’s twenty-fifth state. The mission of this free online encyclopedia is to collect and disseminate information on all aspects of the state’s history and culture and to provide a comprehensive reference work for historians, teachers, students, and others seeking to understand and appreciate Arkansas’s heritage.

The CALS Encyclopedia of Arkansas debuted online to the public in May 2006 as a work in progress. At that time, it contained approximately 700 entries and 900 pieces of media; as of 2017, the site offers more than 5,000 entries and more than 6,700 pieces of media. The CALS Encyclopedia of Arkansas received the 2009 Diamond Award from the Arkansas Historical Association, and in 2013 the mobile version of the website received an Award of Merit from the American Association for State and Local History. In 2013, the CALS Encyclopedia of Arkansas was named a Notable Government Document of 2012 by the Government Documents Round Table of the American Library Association.

Users have come from every continent (including Antarctica) and more than 230 countries (including territories and autonomous provinces). During its first month online, the CALS Encyclopedia of Arkansas had about 47,000 visits; the CALS Encyclopedia of Arkansas now receives more than 1.6 million visits each year.

Major funding for the establishment of the CALS Encyclopedia of Arkansas was provided by the Winthrop Rockefeller Foundation. Over the years, the CALS Encyclopedia of Arkansas has also received funding from the Department of Arkansas Heritage, the Arkansas General Assembly, the Arkansas Humanities Council, the Arkansas Department of Parks and Tourism, and the National Endowment for the Humanities, as well as donations from individuals, foundations, and organizations. CALS has pledged to keep the CALS Encyclopedia of Arkansas in operation in perpetuity.

The CALS Encyclopedia of Arkansas arose from the need for a comprehensive and reliable reference work on Arkansas. Tom Dillard, then curator at the Butler Center for Arkansas Studies at the Central Arkansas Library System, and Tim Nutt, then deputy curator, began planning the CALS Encyclopedia of Arkansas in late 2002. They enlisted the help of Jill Curran to explore the possibility of creating an encyclopedia for the state.

The CALS Encyclopedia of Arkansas had been conceived from the beginning as an inclusive and cooperative effort of historical organizations, state agencies, and interested individuals across the state and beyond.

The team researched other state encyclopedias and then held regional meetings across Arkansas to solicit input from local historical and genealogical societies, county and regional museums, academic institutions, relevant state agencies, and archival and research facilities. The feedback and guidance from these early meetings, both in terms of organizational decisions and editorial content, became the foundation of the Project.

Curran became the project coordinator and Nathania Sawyer joined the team to be the senior editor. In the fall of 2003, the CALS Encyclopedia of Arkansas’s newly formed Oversight and Editorial Boards met for the first time. In December of that year, the Project received a grant of $1.28 million from the Winthrop Rockefeller Foundation, placing it on firm financial footing. Other major contributors followed, including the Department of Arkansas Heritage and the Arkansas Humanities Council. Staffing the project took place in early 2004 as work began in earnest to recruit authors.

The CALS Encyclopedia of Arkansas debuted to the public in May 2006, as a work in progress. It contained approximately 700 entries and 900 pieces of media. During its first month online, the CALS Encyclopedia of Arkansas had more than 47,000 visits and 3.3 million hits.