Linda Sarsour, one of the most prominent Muslim-American activists in New York, says the messages have been arriving by the hour recently.
"Your time is coming."
"A good Arab is a dead Arab."
"You're getting two bullets in your head."
Ms. Sarsour, one of the lead organizers of the Women's March on Washington, has tackled issues like immigration policy, mass incarceration, stop-and-frisk and the New York Police Department's spying operation on Muslims — all of which have largely inured her to hate-tinged criticism.