It dates back to the early days of the post office, which explains its jurisdiction over USPS.
- Click here for the history page on the committee's website.
Note the committee's role in funding the transcontinental railroads.
Some text:
The Committee on Homeland Security and Governmental Affairs as we know today did not begin as a committee charged with overseeing how the federal government operates. In 1816 it was originally formed as the Committee on the District of Colombia and the Committee on Post Office and Postal Roads/Post Office and Civil Service. In 1854, the Committee on Post Office and Postal Roads introduced “A Bill to Provide for the Transportation of the Mails upon Railroads,” one of the first pieces of legislation advocating for the Transcontinental Railroad. Eight years later, the Committee on the District of Columbia created the basis for the D.C. Emancipation Bill, signed by President Lincoln on April 16, 1862 and on display in the Capitol Visitor Center. The Emancipation Proclamation was signed eight months later.
. . . Later, in 1842 the Senate Committee on Retrenchment was created. This Committee stemmed from the Committee on Organization, Conduct, and Expenditures in the Executive Departments which then eliminated forty standing and select committees. These committees were then consolidated in 1921 to form the Committee on Expenditures in the Executive Departments. Its first bill, S 1084, established the system for our National Budget. The Committee on Expenditures in the Executive Department was renamed the Committee on Government Operations in 1952, transforming the Committee’s jurisdiction to overseeing how the federal government operates. In the next two decades the Commitee established itself as the primary investigative body of the Senate. When the Committee on Government Operations was created the Permanent Subcommittee on Investigations (PSI) was also created. PSI led its broad mandate to investigate inefficiency, mismanagement, and corruption in Government. Between 1953 and 1954, PSI Chairman Joseph McCarthy (R-Wis.) held 169 hearings on espionage and subversive activities. In April 1954, Sen. McCarthy clashed with Secretary of the Army Robert T. Stevens, leading to the Army-McCarthy Hearings and the Chairman’s censorship and ultimate political downfall. In the 1960’s and 1970’s the PSI’s investigation of labor unions led the Senate to appoint the Select Committee on Improper Activities which gave public prominence to Senator John F. Kennedy and his brother, the PSI’s lead counsel, Robert F. Kennedy. Government financial scandals and labor racketeering were the PSI’s main focus.