D.C. Code § 39-103
All persons who are permanent or temporary residents of the District of Columbia shall be entitled to the privileges of the District of Columbia Public Library including the use of books and other materials, as a lending or circulating library, subject to rules and regulations established by the Board of Library Trustees. For purposes of this section, persons living outside of the District of Columbia but having regular business or employment or attending school in the District of Columbia shall also be deemed temporary residents of the District of Columbia. Persons residing in jurisdictions outside of the District of Columbia but within the Washington Metropolitan Area (the Washington Metropolitan Area means the Standard Metropolitan Statistical Area "SMSA") who do not qualify as temporary residents in the manner described above may obtain a free library user's card from the District of Columbia Public Library; provided, that the jurisdiction in which such person resides permits District of Columbia residents to obtain a free library user's card from the public library in that jurisdiction. Any person residing in the Washington Metropolitan Area who does not qualify under any of the conditions stated above for the free library user's card may obtain a library user's card from the District of Columbia Public Library upon payment of a fee to be fixed by the Board of Library Trustees.
D.C. Code § 39-103