The Official Congressional Directory (also known as Congressional Directory) is the official directory of the United States Congress, prepared by the Joint Committee on Printing (JCP) and published by the United States Government Printing Office (GPO) since 1887.
Per federal statute (44 USC 721) the Directory is published and distributed during the first session of each new Congress.
[1] It is a designated essential title distributed to Federal depository libraries and the current edition is available for purchase from GPO.
The foreword notes: The Congressional Directory is one of the oldest working handbooks within the United States Government.
With the addition of biographical sketches of legislators in 1867, the Congressional Directory attained its modern format.