Now, the first analysis of enrollment at 70,000 public schools across 33 states offers a detailed portrait of these kindergartners. It shows that just as the pandemic lay bare vast disparities in health care and income, it also hardened inequities in education, setting back some of the most vulnerable students before they spent even one day in a classroom.

The analysis by The New York Times in conjunction with Stanford University shows that in those 33 states, 10,000 local public schools lost at least 20 percent of their kindergartners. In 2019 and in 2018, only 4,000 or so schools experienced such steep drops.

The months of closed classrooms took a toll on nearly all students, and families of all levels of income and education scrambled to help their children make up for the gaps. But the most startling declines were in neighborhoods below and just above the poverty line, where the average household income for a family of four was $35,000 or less. The drop was 28 percent larger in schools in those communities than in the rest of the country.