Updated

The number of people seeking U.S. unemployment aid plunged last week to the lowest level in nearly 42 years, evidence of a strong job market. Yet the drop also reflects seasonal volatility in the data.

The Labor Department says weekly applications for unemployment benefits fell 26,000 to 255,000, the lowest level since November 1973. If the data were adjusted for the growth of the U.S. population since then, last week's figure would likely be an all-time low.

One reason for the drop, however, is that auto plants and other factories close briefly in July to prepare for next year's models. That pushed up applications in the previous two weeks. Now that many factories have reopened, applications have fallen back.