The drop came after New York, California, and several other states ordered a complete shutdown of all non-essential establishments as a social distancing measure to prevent further spread of the coronavirus.
It's the highest level of initial claims the Labor Department has on record since it began adjusting the figures to account for seasonal variations. As the Department of Labor put it, "Nearly every state providing comments cited the COVID-19 virus impacts". But as the pandemic escalates, the government's ability to accurately tally these jobless claims has also been impacted.
Layoffs are sure to accelerate as the US economy sinks into what most economists expect to be deep and painful recession.
The Labor Department reported California's claims at 186,809 last week, and New York's at 80,334, with each of these trailing the almost 379,000 claims filed in Pennsylvania.
In February, the Labor Department reported that unemployment had reached a 50-year low of 3.5 percent.
Job losses are expected to continue in the weeks ahead.