What is the primary purpose of the Preamble in the U.S. Constitution?

The primary purpose of the Preamble in the U.S. Constitution is to articulate the fundamental purposes and guiding principles of the document, effectively explaining what the American government is intended to achieve and the underlying philosophies that govern its structure and function. It sets the tone for the Constitution by outlining key ideas such as justice, domestic tranquility, common defense, general welfare, and securing blessings of liberty. This introductory statement serves to unify the goals of the Constitution and to communicate the framers' intention to establish a government that would serve the people and protect their rights.

In contrast, the other options focus on aspects that are more specific. While outlining the powers of the government is essential, this occurs in the subsequent articles of the Constitution rather than in the Preamble. The establishment of the legislative branch is detailed in Article I, which separately delineates its powers and functions. Likewise, listing the rights of citizens pertains to the Bill of Rights, which was added after the Constitution's original ratification and is not part of the Preamble's intent. Thus, while those elements are integral to the Constitution, they do not capture the primary role of the Preamble, which is to summarize the overarching objectives of the entire document.