The Twenty-third Amendment states as follows:

Section 1

The District constituting the seat of Government of the United States shall appoint in such manner as Congress may direct:

A number of electors of President and Vice President equal to the whole number of Senators and Representatives in Congress to which the District would be entitled if it were a State, but in no event more than the least populous State; they shall be in addition to those appointed by the States, but they shall be considered, for the purposes of the election of President and Vice President, to be electors appointed by a State; and they shall meet in the District and perform such duties as provided by the twelfth article of amendment.

Section. 2.
The Congress shall have power to enforce this article by appropriate legislation.

The Twenty-third Amendment (Amendment XXIII) to the United States Constitution permits the District of Columbia to choose electors for the Presidential and Vice Presidential elections.  The amendment was proposed by Congress on June 17, 1960, and was ratified by the states on March 29, 1961.  The presidential election of 1964 was the first election conducted after the amendment came into effect. 

From the 1870s until 1961, residents of the District of Columbia were denied the right to vote despite paying federal and local taxes and serving in military duty just like residents of all other states.  The United States Constitution contained no provision for representation of citizens of the District of Columbia.  The Twenty-third Amendment gave the District of Columbia residents the right to vote for President and Vice President.  However, the amendment also contained a clause by which the number of the district’s electors could not exceed that of the state with the smallest population.