Which article of the U.S. Constitution establishes the legislative branch?

The legislative branch of the U.S. government is established by Article I of the Constitution. This article outlines the structure and powers of the legislative branch, which is primarily composed of two houses: the Senate and the House of Representatives. Article I specifies how members of Congress are elected, their terms of office, and their responsibilities, including the authority to create laws, levy taxes, and declare war, among other powers. This foundational framework illustrates the importance of the legislative branch as a representative body that reflects the will of the people, contrasting with the judicial and executive branches outlined in the other articles. Understanding this structure is crucial for comprehending the separation of powers and checks and balances that are integral to the functioning of the U.S. government.