History (general)

1. Accessible general resources
2. US History

• General
• Early America
• 19th Century
• 20th Century - present
• US Government​

3. Early World History

• China and the Silk Road
• The Mongol Empire
• Rome: From Republic to Empire 
• Europe in the Middle Ages
• Islamic empires
• Islam and the Crusades
• Black Death
• Renaissance & Reformation
• Explorations
• Global Trade
• Slavery and the Slave Trade
• Scientific Revolution and the Enlightenment

4. Modern World History

• French Revolution
• Industrial Revolution
• Victorian Life
• Nationalism and Socialism
• Imperialism
• World War One
• Effects of the war and start of Great Depression
• Russian Revolution and Beginnings of USSR
• Fascism and National Socialism
• World War Two
  • Propaganda within the war
  • The Holocaust
• Cold War
• Globalization

I've been collecting these resources for more than ten years. The organization corresponds roughly to the unit structure of the courses I teach. Please email me to report links that no longer work. Also, please feel free to recommend links that you feel should be added. 
Thanks!