District of Columbia
2 of the 7 encyclopedias on this shelf carry an entry for District of Columbia. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a tract of land acquired by the national government as a site for the capital. The discomfort of having no permanent seat of government or territory within which Congress might be protected in its deliberations led to the passage of an act in 1790 for the selection of a tract of land on the Potomac. A commission of which Washington was a member laid out a district ten miles square, lying partly in Maryland and partly in Virginia. The two states ceded the desired land to the national government. In 1846 the portion south of the river was receded to Virginia. The present territory is a trifle less than seventy square miles in extent, nearly ten miles of which are swamp and water. Congress met in the new district on the first Monday in November, 1800. Various plans of governing the District have been tried. Under act of June, 1878, local affairs were placed under the management of a commission consisting of two members appointed by the president and confirmed by the Senate and of one army officer detailed by the secretary of war. Congress may be regarded as the city council. One-half the expenses of the district is paid by Congress; the other half is met by local taxation. National property is, of course, exempt from taxation. No elections are held in the district. Citizens live in the district without losing their legal residence in the various states, and may return home to vote. See Washington
Collier's New Encyclopedia (1921)
the Federal district of the United States, containing the National capital. Named for Columbus. Fixed as seat of United States Government in 1790 by an act of Congress. Formed out of Washington co., Md. (64 square miles), a portion of Virginian territory offered the Govern ment being not now included. The United States Government removed to the District in 1800. The city of Washington was captured by the British in 1814, and the Capitol and Executive Mansion were burned. The District was governed by Congress till 1871, when a legislative body of 33 (11 appointed by the President and 22 elected) was created. This form of government was continued till 1878, when the government was invested in the present three commissioners, one of whom must be an army officer, and all of whom are appointed by the President and confirmed by the Senate. Congress makes all laws for the District. Citizens of the District have no vote for National officers. There is but one government for the entire District, with which the city of 30,000 WASHINGTON (q. v.) is now coextensive.