ATLANTA (Reuters) - With street parties, the trumpets and drums of marching bands, speeches and a few political rallies, people across the United States marked Juneteenth this weekend, a jubilee commemorating the end of the legal enslavement of Black Americans. Events started on Friday and continued through Sunday featuring concerts at San Francisco's Golden Gate Park, freedom walks in Galveston, Texas, and jazz music in New York City's Harlem neighborhood. "This is America's holiday, not just African Americans' holiday," said Gerald Griggs, the Georgia state president of the NAACP civil rights organization. "It's the true Independence Day, the day when...