Final answer:
The U.S. Congress began as a one-house legislature under the Articles of Confederation, which had limited powers. The Constitution replaced it, creating today's bicameral legislature with greater authority, and amendments over time have responded to the needs of a changing nation.
Step-by-step explanation:
Evolution of the United States Congress
The United States Congress has undergone significant evolution since the ratification of the Constitution. Initially, under the Articles of Confederation, the national government was formed with a one-house legislature known as the Confederation Congress. This Congress lacked central authority, without the ability to tax, regulate trade, or enforce laws. By 1781, the Articles were ratified, but by 1789, the need for a more effective national government led to the creation of a new Constitution. This Constitution established the bicameral legislature we know today, with specific powers and limitations outlined in Article I, including the authority to levy taxes, borrow money, and regulate commerce. Subsequently, the need for adjustments resulted in the proposal and ratification of various amendments, including the significant Bill of Rights.