The number of Americans applying for unemployment benefits fell but remained at a historically high 847,000 last week, a sign that layoffs keep coming as the coronavirus pandemic continues to rage. Last week’s claims dropped by 67,000, from 914,000 the week before, the Labor Department said Thursday. Before the virus hit the United States hard last March, weekly applications for jobless aid had never topped 700,000. Tempering last week’s bigger-than-expected drop in claims: The four-week moving average — which smooths out week to week gyrations — rose by more than 16,000 last week to 868,000, highest since September.