The number of U.S. workers initially applying for unemployment aid last week dropped below the threshold of 400,000 for the first time since Aug. 6, the U.S. Labor Department reported Thursday.
The department said the advance figure for seasonally adjusted initial claims for jobless benefits was 391,000 last week, a decrease of 37,000 from the previous week's revised figure.
The fresh figure is also the lowest level in nearly six months, signaling improvement in the labor market.
Fewer than 425,000 people applying for aid is consistent with modest job growth, but the number of jobless claims will have to fall to 375,000 or below to signal a sustained drop in the unemployment rate.
Meanwhile, the four-week moving average, which more closely watched claims figure, also declined to 417,000, a decrease of 5,250 from the previous week.
The advance figure for seasonally adjusted insured unemployment during the week ending September 17 was 3.729 million, a decrease of 20,000 from one week earlier.
However, economists said last week's decline did not signal a downward trend as the improvement was partially due to the seasonal adjustment of data affected by Hurricane Irene.
In addition, U.S. economic growth rate was upwardly revised to an annual rate of 1.3 percent in the second quarter of this year from the previous estimate of 1 percent, according to a report released by the Commerce Department on Thursday.
The weekly figures of jobless benefits application reflect the level of layoffs and indicate real-time condition of the American job market.