India, Nov. 7 -- "Indians go home". That was the mantra of the Make America Great Again (MAGA) crowd this year. Indian Americans listened, and they did go home, not to India, but back to the Democratic Party they have long supported. In doing so, they have begun to redraw the map of American politics. And they may finally be ready to shed their meekness and speak up.

They have just shaken the foundation of New York City. Zohran Mamdani, 34, the son of filmmaker Mira Nair, won the mayor's race by a landslide, defeating former governor Andrew Cuomo. He will be the city's first Muslim mayor, its first of Indian descent, and its youngest leader in more than a century.

His victory marks the moment a community that had long stayed quiet under...