Public libraries continue to face deep cuts in budget, staff and hours as states and municipalities struggle with a recession that is reluctant to loosen its grip.

Studies we conducted between 2004 and 2008, and then updated in 2010 provided abundant evidence that libraries and the services they provide are especially important during times of recession.

Our data show that every year over the past two decades, use of public libraries has increased by over 2 billion visits annually. In fact, when remote access to public libraries through the Internet is included, the number of visits per capita has more than doubled during the same two decades.

When we looked specifically at the previous two recessions, we saw that growth in visits to libraries as well as services they offered rose well above previous levels.

Use also remained high following a recovery as new and continuing users discovered the value of library services.

The extensive use of libraries during recessions is partially the result of public libraries' adjusting services to fill recession-related needs.

It also stems from a growing public confidence in the trustworthiness of information provided by libraries, the quality of services offered and the convenient access.

Contrary to the popular myth that public libraries serve primarily the recreational needs of their communities, the overwhelming majority (over 70 percent) of visits to public libraries are for non-recreational purposes.

• Nearly a quarter of adult visits are to address personal or family-related needs, such as help with health and wellness issues, personal finance, how to make or fix something, or to keep current with news or find jobs.

• The proportion of visits that are job-related increased from 3 percent in 2009 to 11 percent in 2010. Most public libraries now provide access to jobs databases, civil-service-exam materials, software to help create résumés, and other employment-related information. They help users complete online job applications and offer helpful classes.

• About one in eight visits is by a small business — and even some large ones — to conduct research and to seek information and support regarding legal, financial and operational concerns. Public libraries have often helped small businesses get started.

• Some one-third of visits are for educational needs — and not just for children doing homework or adults continuing their education. Teachers often use public libraries for their continued education or to keep up with professional literature; they also rely on public libraries to prepare for class or lectures.

Recessions continue to place a burden on public libraries and the communities they serve. Without budgets for new purchases, collections grow stale and outdated for lack of new volumes and updates.

When a library closes, a user bears an additional burden: He or she winds up spending about 45 additional minutes and more than $20 per visit to find and use alternative sources of information.

Public libraries have adapted to reduced collection purchases by relying heavily on interlibrary borrowing. Many now also have formal partnerships with government agencies and industries to meet the growing need for access to government information, services and forms, or for help understanding government programs.

Finally, public libraries in most communities have been able to accommodate sharp increases in service offerings and usage because of their committed and highly motivated staff who believe in their mission to serve the public.

Clearly, public libraries are essential to all sectors of society and for many different types of use. Do not sell this essential community resource short!

José-Marie Griffiths, an expert in information sciences, is vice president for academic affairs at Bryant University. Donald W. King, a statistician and entrepreneur, is an honorary university professor at Bryant University. They are leading researchers in information science and authors of 14 books, including, "A Strong Future for Public Library Use and Employment" (American Library Association Editions, June 2011).