The United States federal executive departments are among the oldest primary units of the executive branch of the federal government of the United States -- the Departments of State , War , and the Treasury all having been established within a few weeks of each other in 1789 .
The United States federal executive departments are among the oldest primary units of the executive branch of the federal government of the United States -- the Departments of State , War , and the Treasury all being established within a few weeks of each other in 1789 .