[1] The library's foundation was laid in 1941, but was not completed until 1947 due to World War II.

The architects were William Harold Lee of Philadelphia and Crowell & Lancaster of Bangor.

The Folger Library is a depository for a number of collections, including the multi-generation political families of the Williamsons and the Hamlins.

[4] It is also home to the works of writer Stephen King, journalist Ralph W. 'Bud' Leavitt Jr. and politician William Cohen.

[3] It houses significant holdings related to the environment, resource conservation, and related policy, such as the Great Northern Paper Company Records, the Dickey-Lincoln Hydro Project Collection, and the W. Kent Olson Conservation Papers.