Inside the ancient town hall of Siena, Italy, the walls hold a series of magnificent 14th-century frescoes showing the effects of good government and bad. One side depicts a prosperous city-state, where justice and tolerance prevail in the Tuscan countryside. The other is ruled by a horned, fanged figure, the streets deserted and scary.

We saw our own version of this allegory with the two Americas this week — one going backward, the other stepping into tomorrow. We saw a retreat to bigotry in states dooming themselves to decline. And in other states, we saw a way for people to get around a do-nothing Congress controlled by Know-Nothing throwbacks.

First, the good. On Monday, Gov. Andrew M. Cuomo signed a bill that will eventually raise the minimum wage to $15 an hour, lifting the earnings of 2.3 million New Yorkers, and he authorized one of the strongest paid parental leave laws in the nation. On the same day, Gov. Jerry Brown of California put his signature to a $15 minimum wage plan in the most populous state. Then San Francisco became the first place in the United States to require businesses to provide paid leave for new parents.

What had seemed impossible just a few years ago is now rolling through cities and states led by forward-looking politicians. Together, these changes amount to a “revolution in the workplace,” as one exultant activist put it. But let’s not get too excited: The United States remains the only developed country in the world that does not mandate paid parental leave.