* Values presented are for the 50 U.S. states and the District of Columbia. Calculations were performed on all surveyed libraries, not just those meeting Institute of Museum and Library Services criteria for public libraries. Expenditure amounts have been adjusted for inflation using the annual gross domestic product deflators (seasonally adjusted) produced by the U.S. Department of Commerce, Bureau of Economic Analysis. Deflators were downloaded from the website of the Federal Reserve of St. Louis at http://research.stlouisfed.org/fred2/series/GDPDEF/downloaddata?cid=21.
** Includes expenditures for binding, supplies, repair or replacement of existing furnishings and equipment, and costs of computer hardware and software used to support library operations or to link to external networks, including the Internet; also includes expenditures for service contracts, such as costs of operating and maintaining physical facilities, and fees paid to consultants, auditors, architects, attorneys, and so on.

Source:U.S. Department of Education, National Center for Education Statistics, Public Libraries Survey (1995–2005); Institute of Museum and Library Services, Public Libraries in the United States Survey (2006–2014).