The Federal Reserve was created in 1913 to act as a central organization to regulate the money supply of the United States and to establish moderately long term interest rates. In the years before the Federal Reserve, financial panics were common and extremely detrimental to the growth of the economy; the Panic of 1807 is usually considered the direct tipping point. Over the years, the power of the Federal Reserve has greatly expanded, particularly during the Great Depression Era, to try to prevent economic depression and recession.

President Garfield was assassinated by Charles Guiteau. Guiteau, who wrote an essay supporting Garfield’s campaign, believed he should be rewarded with a position in Garfield’s government, and when this was not granted he enacted personal revenge. The motivation behind the assassination was one of the main factors that inspired the government to enact into law a bill that stated that government jobs should be awarded on the basis of merit alone, and not as gratitude for political favors. John Wilkes Booth was convicted of Lincoln’s assassination, Leon Czolgosz with the assassination of William McKinley, Lee Harvey Oswald with the assassination of John F. Kennedy. Robert E. Lee was a Confederate general, and war hero, during the American Civil War.

The Pendleton Act was established in 1883 and issued to ensure that government jobs were awarded on the basis of merit, or qualification, alone rather than based on political ties or personal relationships. It can be seen as part of the public’s general reaction to the assassination of James Garfield by a government employee who acquired his job due to political privilege and not based on merit.

The U.S. Postal Service is an example of a government run corporation, a business run by government. An independent regulatory agency would be something like the Federal Communications Commission, which regulates TV and media broadcasts. Government corporations usually provide a specific service and are not influenced by special interests. Government corporations tend not to trade in stocks or dividends.

Federal bureaucrats do not engage in public policy creation, their sole purpose is to implement policy. The bureaucracy implements laws made by the legislature and executive actions, they do not advise the President or the Cabinet, nor compete in the private sector. Congressmen protect and represent the interests of their constituencies.

The National Parks Service is under the Department of the Interior, which primarily deals with natural resources and public lands within the United States. It is sometimes confused with the National Forestry Service, which is a separate agency that is located in the Department of Agriculture.

The Postmaster General is the head of the U.S. Postal Service. The Postmaster General used to an office given out as a political reward to a supporter of the president and because the office was appointed by the president it was in the Cabinet and in the Presidential Line of Succession from 1829 until 1971. In 1971 the Postal Service went through changes and became an independent agency outside of the executive branch so the position was taken out of the Cabinet and the Line of Succession. All other offices that were listed in the question do hold the status of Cabinet-rank, even if not in the Presidential Line of Succession.

Soon after the September 11^th, 2001 terrorist attacks President Bush established the Office of Homeland Security to determine how to discover and prevent future terrorist attacks. The Homeland Security Act of 2002 officially created the Department of Homeland Security as a new Cabinet agency and brought together various agencies that concerned security and law enforcement, previously under other departments, and placed them within this new agency.

The Department of War was established in 1789 to handle the military affairs of the young nation and was headed by the Secretary of War.  The Navy split from it after it was given its own department in 1798, but the War Department continued to govern the Army and later the Army Air Corps. In 1947 the War Department was split into the Department of the Army and the Department of the Air Force in order to form the National Military Establishment with the Department of the Navy. All three departments were combined in 1949 under the Department of Defense.

The agency was originally in the Treasury Department, as its founding purpose was to stop counterfeiters. The agency was moved to the then-recently established Department of Homeland Security in 2003 so that it could focus on threats against the president and other national leaders.