The great divergence is rapidly expanding—and President Joe Biden’s window to reverse it is narrowing.

Since the 1960s, Congress and federal courts have acted mostly to strengthen the floor of basic civil rights available to citizens in all 50 states, a pattern visible on issues from the dismantling of Jim Crow racial segregation to the right to abortion to the authorization of same-sex marriage. But now, offensives by red-state governments and GOP-appointed federal judges are poised to retrench those common standards across an array of issues. The result through the 2020s could be a dramatic erosion of common national rights and a widening gulf—a “great divergence”—between the liberties of Americans in blue states and those in red states.