America's pandemic murder surge: what happened?

As covid-19 spread around the world, a different sort of epidemic swept across America. The murder rate spiked by 30% in 2020, compared with a year earlier—and it kept increasing in 2021. This year, it looks unlikely to decrease significantly, threatening to become the new baseline. What is it about America that led to more murders, when many countries’ rates remained flat or even decreased—and how can the country tackle this huge spike in violence?