Most college and university libraries arrange their books using the Library of Congress Classification system.
This system uses the letters of the alphabet to distinguish major subject divisions.
For History, note especially:
D call numbers = World History. Floor 3 - North side
E call numbers = United State History. Floor 3 -- East side
E 185 call numbers = African American History. Floor 3 -- East side
E 440 - 450 call numbers = Slavery & Anti-Slavery History. Floor 3 -- East side
F call numbers = State and Local U.S. History; Canadian History;
Latin American History. Floor 4 -- North side
H call numbers = Social Sciences. -- Floor 4
HQ call numbers -- Floor 4 -- south side.
