As the seat of the Federal Executive, Legislative, and Judicial branches of the Federal government, the Washington, D.C. economy gains from their participants, traffic, and direct and indirect spending.
Government has always been its major economic contributor, but its dominance varies with political administrations with repeated sequesters, shutdown, and budget cuts. Still, looking at its components, the impact is significant.
The Executive Branch survives to some extent on the policies and initiatives of the president in office. But, over four thousand, including members of Defense, Homeland Security, Treasury, Health and Human Services, and other agencies, are directly connected with the Executive office.
Many employees of the agencies are in Civil Service jobs protected by regulations and unions. Presidential initiatives to freeze hiring are usually offset by expansion in other areas. The total number of Civilian employees at Cabinet agencies is over 170,000. The largest is Homeland Security with approximately 25,000 positions.