How art, history and philanthropy can bridge Americans' political divisions

A “Black Lives Matter” flag billows from my neighbor’s porch. At a home across the street, a “Trump 2020” flag flies atop a pole. My house sits between the two, with a small yard sign promoting the Big Brothers Big Sisters mentoring program, an advocacy statement that represents a kind of idea — helping vulnerable youth — that draws Americans of all political persuasions together, no matter which flag they fly.

It’s the kind of thing we need to talk about much more often.

Even as partisan disagreements have intensified,...