All told, the people charged with plotting attacks or trying to travel to fight for the Islamic State lived in nearly two dozen states. For the most part, they were not clustered together, although there were about a dozen from a Somali enclave in Minneapolis.
Almost all of the accused were American citizens or permanent residents. About 40 percent had converted to Islam. Nearly three-quarters were under 30, and all but 11 were male.
“ISIS, in addition to being a force in the Middle East, is essentially a global gang preying upon alienated youth and providing an identity for self-selecting men and women who are isolated, angry and, at the same time, in search of a mission in life,” Ms. Greenberg said.