The number of Americans applying for unemployment benefits fell last week to near a four-year low, but the drop may have been distorted by seasonal factors, the government reported Thursday. The Labor Department said jobless claims fell 35,000 last week to 353,000, the biggest weekly drop since February 2011. The four-week moving average of jobless claims - considered a better measure of labor-market trends because it reduces weekly volatility - fell 8,750 to 367,250, the lowest level since the end of March. Jobless-claim readings have been volatile this month because of the timing of the annual auto-factory shutdowns for retooling. The reading hit a four-year low in the second week of July at 352,000. This year, automakers are undertaking fewer temporary plant shutdowns. Jobless claims are a measure of the pace of layoffs. When claims consistently remain below 375,000, it typically indicates that hiring is strong enough to lower the unemployment rate, currently at 8.2 percent. The job market has weakened over the past three months. Employers added an average of only 75,000 jobs per month from April through June, down from a stronger 226,000 per month in the first quarter.