An impression seems to prevail that the interests of persons having business with the executive government require that they should have personal interviews with the President or heads of Departments. As this impression is believed to be entirely unfounded, it is expected that applications relating to such business will hereafter be made in writing to the head of that Department to which the business may have been assigned by law. Those applications will in their order be considered and disposed of by heads of Departments, subject to the approval of the President. This order is made necessary by the unusual numbers of persons visiting the seat of Government. It is impracticable to grant personal interviews to all of them, and desirable that there should be no invidious distinction in this respect. Similar business of persons who can not conveniently leave their homes must be neglected if the time of the executive officers here is engrossed by personal interviews with others.
Andrew Johnson, Executive Order Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/203002