President Trump has cut hundreds of thousands of jobs from the federal work force, disproportionately affecting Black employees.When President Trump started dismantling federal agencies and dismissing rank-and-file civil servants, Peggy Carr, the chief statistician at the Education Department, immediately started to make a calculation. She was the first Black person and the first woman to hold the prestigious post of commissioner of the National Center for Education Statistics. As a political appointee, she knew there was a risk of becoming a target. But her 35-career at the department spanned a half dozen administrations, including Mr. Trump’s first term, and she...