Until the late 19th century, creation was taught in nearly all schools in the United States, often from the position that the literal interpretation of the Bible is inerrant. With the widespread acceptance of the scientific theory of evolution in the 1860s after being first introduced in 1859, and developments in other fields such as geology and astronomy, public schools began to teach science that was reconciled with Christianity by most people, but considered by a number of early fundamentalists to be directly at odds with the Bible.
In the aftermath of World War I, the Fundamentalist-Modernist Controversy brought a surge of opposition to the idea of evolution, and following the campaigning of William Jennings Bryan several states introduced legislation prohibiting the teaching of evolution. Such legislation was considered and defeated in 1922 in Kentucky and South Carolina, in 1923 passed in Oklahoma, Florida, and notably in 1925 in Tennessee, as the Butler Act. The American Civil Liberties Union (ACLU) offered to defend anyone who wanted to bring a test case against one of these laws. John T. Scopes accepted, and he started teaching his class evolution, in defiance of the Tennessee law. The resulting trial was widely publicized by H. L. Mencken among others, and is commonly referred to as the Scopes Trial.
Scopes was convicted; however, the widespread publicity galvanized proponents of evolution.
When the case was appealed to the Tennessee Supreme Court, the Court overturned the decision on a technicality (the judge had assessed the fine when the jury had been required to). Although it overturned the conviction, the Court decided that the law was not in violation of the First Amendment to the United States Constitution. The Court held:
We are not able to see how the prohibition of teaching the theory that man has descended from a lower order of animals gives preference to any religious establishment or mode of worship. So far as we know there is no religious establishment or organized body that has its creed or confession of faith any article denying or affirming such a theory. -- John Thomas Scopes v. The State 154 Tenn. 105, 289 S.W. 363 (1927)
The interpretation of the Establishment Clause of the First Amendment up to that time was that Congress could not establish a particular religion as the State religion. Consequently, the Court held that the ban on the teaching of evolution did not violate the Establishment Clause, because it did not establish one religion as the "State religion." As a result of the holding, the teaching of evolution remained illegal in Tennessee, and continued campaigning succeeded in removing evolution from school textbooks throughout the United States.