The report "Program on Extremism" published by George Washington University on December 1 said that the number of other Americans who passively "consume" Islamic State propaganda runs to"several thousand," though they are not necessarily active supporters of the group.
The report noted that the Twitter is most widely used by these Americans to support the group.
Other social media channels like Facebook, Google+ and Tumblr, Kik, Telegram, surespot and the dark web is also used by these American ISIS activist, added the report.
They have established themselves as nodes and active enough to lead the voice to promote ISIS theme.
These supporters have created a "unique innovation" in militant messaging. Although American social media accounts linked to ISIS are regularly suspended.
Operators of suspended accounts usually set up and start using a newly created account, using only a variation of the previous user name, "within hours" of most suspensions, it said.
"US authorities are currently pursuing 900 terrorism-related investigations in all 50 US states," said Lorenzo Vidino, one of the study`s principal authors.
According to report, US authorities charged 71 individuals for ISIS-related offences since March 2014, with 51 of those arrests occurring in 2015.