Final answer:
Article I of the U.S. Constitution establishes the legislative branch, consisting of a Congress with two houses: the Senate and the House of Representatives.
Step-by-step explanation:
The legislative branch of the United States federal government is established by Article I of the U.S. Constitution. This Article mandates a bicameral Congress, consisting of two houses: the Senate and the House of Representatives. The primary role of Congress is to make laws for the nation. Article I, Section 1 clearly vests all legislative powers in Congress, laying the foundation for how the Senate and House operate and the powers they hold.
Article II, on the other hand, outlines the powers of the President, establishing the executive branch. When comparing Articles I and II, one can notice that the framers of the Constitution dedicated more words and precision to defining the powers of Congress than those of the President. The creation of the legislative branch was a key element in the separation of powers, ensuring that law-making remained in the hands of a representative body.