Sezon 23
Bölümler
1 God in America (Parts 1–2) 11 Eki 2010 
2 God in America (Parts 3-4) 12 Eki 2010 
3 God in America (Parts 5-6) 13 Eki 2010 
4 Robert E. Lee 3 Oca 2011 
5 Dinosaur Wars 17 Oca 2011 
6 Panama Canal 24 Oca 2011 
7 The Greely Expedition 31 Oca 2011 
8 Triangle Fire 28 Şub 2011 
9 The Great Famine 11 Nis 2011 
10 Stonewall Uprising 25 Nis 2011 
11 Soundtrack for a Revolution 9 May 2011 
12 Freedom Riders 16 May 2011