Around the time that Donald Trump became the Republican Party’s nominee for president, my wife and I visited the American Labor Museum at the Botto House National Landmark, in Haledon, New Jersey. Several Muslim children, three whose parents came from Bangladesh and another whose parents came from Morocco, were tending the museum’s Immigrant Garden. Education director Evelyn Hershey worked beside them, highlighting the garden’s history, redirecting the hose. It was hard to watch her young helpers without wondering how fraught the words “immigrant” and “Muslim” might soon be for them.

The first people to plant here were Pietro and…