Constitution Day and Citizenship Day, as defined by the Law Library of Congress, is observed each year on September 17 to commemorate the signing of the Constitution on September 17, 1787, and “recognize all who, by coming of age or by naturalization, have become citizens." For legislation, Presidential Proclamations, and Executive Orders pertaining to this commemoration, visit the Law Library of Congress' Constitution Day and Citizenship Day page.
Online Resources about the Constitution
The Constitution of the United States: A Transcription from the National Archives
The Constitution Annotated from the Library of Congress. This site premiered on September 16, 2019 and has additional features and upgrades planned.
U.S. Constitution presented with explanatory text from the Legal Information Institute of Cornell Law School
Constitution of the United States: Primary Documents in American History from the Library of Congress
The US Constitution video and transcript from the Khan Academy
Online Resources about U.S. Citizenship
Citizenship Resource Center provides study materials and resources