Four years ago I wrote a research paper on discrimination against atheists in America. I can post it if anyone wants, but it's 10 pages long and I can just summarize the evidence.

*#1: Anti-atheist provisions in state constitutions of Arkansas, Maryland, North Carolina, Pennsylvania, South Carolina, Tennessee, and Texas. Delaware grants freedom of religion with the additional clause that “it is the duty of all men frequently to assemble together for the public worship of Almighty God” and that “the prosperity of communities” depends on “piety and morality.”

*#2: Surveys showing atheists are more distrusted than Muslims and that many people would not vote for an atheist.

*#3: Cold war hysteria leads to "In God We Trust" on money and "Under God" in Pledge of Allegiance.

*#4: The Boy Scouts

*#5: Atheists discriminated against in child custody hearings