The following is a selected list of historical U.S. government documents online. Other documents and collections can be found using the Clearinghouse of Government Documents Digital Projects.
A Century of Lawmaking for a New Nation: U.S. Congressional Documents and Debates, 1774-1873 includes:
the Journals of the Continental Congress (1774-89);
the Journals of the House of Representatives (1789-1875) and the Senate (1789-1875), including the Senate Executive Journal (1789-1875);
the debates of Congress as published in the Annals of Congress (1789-1824), theRegister of Debates (1824-37), Congressional Globe (1833-73), and Congressional Record (1873-75);
the Statutes at Large (1789-1875);
Avalon Project: Documents in Law, History and Diplomacy from the Yale Law School. This site only provides the text of documents, not facsimiles of the original documents.
Core Documents of U.S. Democracy: includes the Articles of Confederation, The Bill of Rights, The Constitution of the United States of America, The Declaration of Independence, Emancipation Proclamation, The Federalist Papers, The Gettysburg Address.
Historical Publications of the United States Commission on Civil Rights includes historical and current USCCR publications.
Milestone Documents: "100 milestone documents, compiled by the National Archives and Records Administration, and drawn primarily from its nationwide holdings. The documents chronicle United States history from 1776 to 1965."