D.C. Code § 2-1101
The Congress hereby declares that, because the District which is the seat of the government of the United States and has now become the urban center of a rapidly expanding Washington metropolitan region, the necessity for the continued and effective performance of the functions of the government of the United States at the seat of said government in the District of Columbia, the general welfare of the District of Columbia and the health and living standards of the people residing or working therein and the conduct of industry, trade, and commerce therein require that the development of the District of Columbia and the management of its public affairs shall, to the fullest extent practicable be coordinated with the development of the other areas of the Washington metropolitan region and with the management of the public affairs of such other areas, and that the activities of all of the departments, agencies, and instrumentalities of the federal government which may be carried out in, or in relation to, the other areas of the Washington metropolitan region shall, to the fullest extent practicable, be coordinated with the development of such other areas and with the management of their public affairs; all toward the end that, with the cooperation and assistance of the other areas of the Washington metropolitan region, all of the areas therein shall be so developed and the public affairs thereof shall be so managed as to contribute effectively toward the solution of the community development problems of the Washington metropolitan region on a unified metropolitan basis.
D.C. Code § 2-1101