The ranks of Americans queuing up to claim jobless benefits for the first time grew by 21,000 last week as expected, government data showed on Thursday, while continued claims declined to the lowest level in four years. Initial claims for state unemployment aid rose to 320,000, matching Wall Street forecasts, compared with a revised 299,000 the previous week, the Labor Department said. This number had initially been reported at 296,000. A Labor Department official said there were no special factors to take into account when examining the numbers but cautioned that claims data were usually volatile around holiday periods like school spring break and summer vacations. A four-week moving average of claims, which smooths weekly volatility to provide a better sense of underlying job-market trends, fell by 8,000 to 323,000.