Recent Recommendations by the Judicial Conference for New U.S. Circuit and District Court Judgeships: Overview and Analysis [September 3, 2019] [open pdf - 1MB]
From the Introduction: "Article III, Section I of the Constitution provides that the 'judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish.' Consequently, Congress determines through legislative action both the size and structure of the federal judiciary. For example, the size of the federal judiciary is determined, in part, by the number of U.S. circuit and district court judgeships authorized by Congress. Congress has, at numerous times over the years, authorized an increase in the number of such judgeships in order to meet the workload-based needs of the federal court system. The Judicial Conference of the United States, the national policymaking body of the federal courts, makes biennial recommendations to Congress to assist it in identifying any U.S. circuit and district courts that may be in need of additional judgeships. The most recent recommendations for new U.S. circuit and district court judgeships were released by the Judicial Conference in March 2019."
CRS Report for Congress, R45899
Congressional Research Service: https://crsreports.congress.gov/