Congress has many enumerated powers. Spending money is not one of them. The Founders had just fought a war over unjust taxation to support the head of state's

Congress has many enumerated powers. Spending money is not one of them. The Founders had just fought a war over unjust taxation to support the head of state's pet projects. Thus they required all funds to be appropriated by Congress. But it is still the head of state that actually spends them. The Treasury has always been part of the Executive branch, ever since Alexander Hamilton led the Treasury under George Washington. Our country is built on checks and balances. The Executive controls the Treasury and spends money out of it, but is checked by the Congress, because the Executive cannot spend money without it first being appropriated.