Founders Online
This is an online database of correspondence and other writings by the founders, provided by the National Archive. Letters and papers can be browsed by author, recipient, period, and keyword.
The Gilder Lehrman Institute of American History: History by Era
http://www.gilderlehrman.org/history-by-era/new-nation-1783-1815
This is a comprehensive survey of American history organized by era. The site includes essays, primary sources, and teaching guides. Subscriptions are free for K-12 educators and students.
The Avalon Project: Documents in Law, History, and Diplomacy
This is a collection of seminal...