Last week at Delaney Hall in Newark, New Jersey, protesters sang at police during a sit-in. It was just months after the Resistance Revival Chorus packed 500 people into Middle Church in Manhattan’s East Village for an ICE Out sing-in. At that event back in February, 150 people who couldn’t get inside stayed on the sidewalk, singing along from printed lyric sheets. Neighbors filed out of their apartments to join them. Hundreds more watched the livestream from across the country. Something loud is happening, and it’s not just happening in the New York metro area. Across the country, people are...