SOMERSET COUNTY, Pa.—Joe Biden visited the Flight 93 National Memorial on Friday, talking briefly with other visitors but spending most of his time interacting with families of people who died on Sept. 11, 2001. He arrived around 1 p.m., several hours after President Donald Trump took part in a private ceremony with loved ones of passengers and crew members who died while thwarting hijackers that hoped to crash the plane into the U.S. Capitol. Biden was accompanied by his wife, Jill, with both wearing face masks. Speaking to one of the families, the Democratic candidate for president mentioned his own...