WASHINGTON — The unemployment rate dropped unexpectedly in January to 9.7 percent, while employers shed 20,000 jobs, according to a report that offered hope the economy will add jobs soon.

The unemployment rate dropped from 10 percent because a survey of households found the number of employed Americans rose by 541,000, the Labor Department said today. The job losses are calculated from a separate survey of employers.

Excluding the beleaguered construction industry, which shed 75,000 jobs, the private sector added 63,000 positions.

The unemployment rate fell to its lowest level since August. John Silvia, chief economist at Wells Fargo, said the decline wasn't a result of a shrinking labor force, which has held the rate down in previous months.

The department also revised its past employment estimates to show that job losses from the Great Recession have been much worse than previously stated. The economy has shed 8.4 million jobs since the downturn began in December 2007, up from a previous figure of 7.2 million.

That's the most jobs lost in any recession, as a percent of total employment, since World War II.