In the two weeks since the slaughter of 17 students and adults in Parkland, Fla., not much has changed in the way the country regulates guns. Anyone who could buy an assault rifle on Feb. 13 still can today. And yet, even with Republicans in control of Congress and the White House, the ground seems to be shifting in the direction of gun safety advocates who have been stymied for years. Whether this shift will last and what its long-term impact will be remain unknown. But the movement that began among the teenage survivors of the shooting at Marjory Stoneman Douglas High School, which hopes to bring as many as a half-million marchers to Washington next month, has become the latest in a long tradition of movements for social change that have transformed the politics of issues that were once seen as set in stone, from slavery to the casual acceptance of sexual harassment.
