The U.S. job market finished 2012 chugging along in the same low gear of the past two years, stoking nervousness over sluggish economic growth ahead as new risks from Washington loom over the coming weeks.

Employers added 155,000 jobs in December, in line with the average gains of 2011 and 2012. The unemployment rate, which is derived from a separate survey of households, sat at 7.8%, with the labor force rebounding from a drop tied to superstorm Sandy a month earlier.

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