Fifty years ago, every state criminalized homosexual sex, and even the American Civil Liberties Union did not object. The federal government would not hire people who were openly gay or permit them to serve in the military. Police routinely raided gay bars. Only a handful of gay-rights organizations existed, and their membership was sparse. Most Americans would have considered the idea of same-sex marriage facetious.
Today, opinion polls consistently show a majority of Americans endorsing such marriages; among those aged 18 to 29, support is as high as 70 percent. President Barack Obama has embraced marriage equality. Last November, for the first time, a majority of voters in a state—in fact, in three states—approved same-sex marriage, and in a fourth, they rejected a proposed state constitutional amendment to forbid it.
How did support for gay marriage grow so quickly—to the point where the Supreme Court may deem it a constitutional right in 2013?