The fatal mugging of Barnard College freshman Tessa Majors in Morningside Park last week — allegedly at the hands of three boys ages 13 and 14 — came as little surprise in a neighborhood already reeling from rising crime and roving bands of violent youths. The park was the most dangerous in the city for muggings in the first nine months of 2019, logging 11 robberies in that period, according to NYPD statistics. By comparison, there were 10 reported muggings in Brooklyn’s Prospect Park and nine in Claremont Park in The Bronx in that same period. Reports of violent crime...