Original: Founded by Justin Winsor , Charles Ammi Cutter , Samuel S. Green , James L. Whitney , Melvil Dewey ( Melvil Dui ) , Fred B. Perkins and Thomas W. Bicknell in 1876 in Philadelphia and chartered in 1879 in Massachusetts , its head office is now in Chicago .
Simplified: Justin Winsor , Charles Ammi Cutter , Samuel Swett Green , James L. Whitney , Melvil Dewey , Fred B. Perkins and Thomas W. Bicknell began the organization in 1876 . It began in Philadelphia , but its head office is in Chicago now .