While the United States Constitution's First Amendment identifies the rights to assemble and to petition the government, the text of the First Amendment does not make specific mention of a right to association. Nevertheless, the United States Supreme Court held in NAACP v. Alabama (1958) that freedom of association is an essential part of freedom of speech because, in many cases, people can engage in effective speech only when they join with others.
from: https://en.wikipedia.org/wiki/Freedom_of_association