Final answer:
The structure of Congress was decided by the Great Compromise, also known as the Connecticut Compromise, during the Philadelphia Convention of 1787. It established a bicameral legislature with proportional representation in the House of Representatives and equal representation in the Senate.
Step-by-step explanation:
The Great Compromise, also known as the Connecticut Compromise, decided the structure of Congress. This compromise was developed to calm the storm of debate between large and small states regarding the allocation of power in the new government.
The Great Compromise proposed a bicameral legislature with a dual system of representation: in the upper house, the Senate, each state would have two members, while in the lower house, the House of Representatives, membership would be based on each state's population size. This appeased both large states, which benefitted from proportional representation, and small states, which were assured equal representation in the Senate.
The Three-Fifths Compromise, while related to the structure of representation, specifically addressed the issue of how slaves would be counted for representation and taxation purposes. It determined that each slave would count as three-fifths of a person. Although this compromise was a critical element in the debates during the Philadelphia Convention of 1787, it did not dictate the structure of Congress as did the Great Compromise.
The Commerce Compromise was related to regulation of trade and taxation, particularly concerning the slave trade and import duties. It granted Congress the power to regulate interstate and international commerce and stipulated that no tariffs would be placed on exported goods from any state, and that no laws restricting the slave trade would be passed before 1808. While this had implications for the powers of Congress, it was the Great Compromise that established Congress's actual structure.