The number of people killed on the nation’s highways rose 4.6% in the first nine months of 2020 despite coronavirus lockdowns that curtailed driving early in the year. The National Highway Traffic Safety Administration estimates that 28,190 people died in traffic crashes from January through September of last year, up from 26,941 in the same period of 2019. Final statistics for the full year won’t come out until fall. Authorities blamed the increase on risky driving behavior that developed when there were few vehicles on the road early in the pandemic.