In his speech, Obama invoked the history of struggles for equality with a remarkable triptych: Seneca (women’s rights), Selma (black rights), and Stonewall (gay rights). And there has been remarkably little blowback — a sign of how much the country has changed.

What many people may not realize is how recent those changes are. Gay rights may be relatively obvious — it’s just 8 years since opposition to gay marriage arguably played a significant role in Bush’s victory. But the big changes on the racial front are also more recent than widely imagined (obligatory disclaimer — yes, there’s a lot of racism remaining, and it can be truly ugly; we’re just talking about relative changes)....