By Lucia Mutikani

WASHINGTON (Reuters) - The U.S. unemployment rate fell to a nine-year low of 4.6 percent in November, as employers added another 178,000 jobs, making it almost certain that the Federal Reserve will raise interest rates later this month.

The unemployment rate hit its lowest level since August 2007 because more people found work but also because the labor force shrank as more people retired, lowering the number of working-age people in the labor force to 62.7 percent.

U.S. nonfarm payrolls increased by 178,000 jobs last month after increasing by 142,000 in October, the Labor Department said on Friday.

Economists had forecast payrolls rising by 175,000 last month and the unemployment rate remaining unchanged at 4.9 percent.

"The decline in the unemployment rate and the unambiguous decrease in labor market slack are likely to place further upward pressure on inflation. This report easily clears the bar for a December rate hike," said Michael Gapen, chief economist at Barclays in New York.

Wages slipped for the first time in nearly a year though after two straight months of increases. Economists partially blamed the drop in average hourly earnings on a calendar quirk, which they expect Fed officials will overlook at their Dec. 13-14 policy meeting.

Average hourly earnings fell three cents, or 0.1 percent, after rising 0.4 percent in October and gaining 0.3 percent in September. Average hourly earnings fell for workers in mining, manufacturing and utilities in November.

Last month's drop in wages lowered the year-on-year gain to 2.5 percent in November from October's 2.8 percent increase, which was the largest rise in nearly 7-1/2 years.

"This is likely to be a temporary setback, as further tightening in labor market conditions should increase competition for skilled labor and support stronger wage growth," said Jim Baird, chief investment officer at Plante Moran Financial Advisors in Kalamazoo, Michigan.

A broad measure of unemployment, that includes people who want to work but have given up searching and those working part-time because they cannot find full-time employment, fell two-tenths of a percentage point to 9.3 percent, the lowest level since April 2008.

After a rally of about 6.0 percent in the past three weeks, U.S. stocks ended little changed in the wake of the jobs data on Friday.

U.S. Treasury bond yields on Friday eased from multi-month highs after the worst sell-off in debt markets in nearly eight years following the election of Donald Trump as U.S. president in early November.

Trump's plan to increase infrastructure spending and cut taxes could encourage companies to boost hiring and spur an even faster pace of economic growth over the coming years, analysts said.

BROAD GAINS

Job gains have slowed from an average of 229,000 per month in 2015 to an average of 180,000 this year as the labor market nears full employment. Still, the monthly increases are more than enough to absorb new entrants into the labor market.

Fed Chair Janet Yellen has said the economy needs to create just under 100,000 jobs a month to keep up with growth in the working-age population.

"It is not that firms aren't trying to hire, they just cannot find qualified workers at the wages they want to pay," said Joel Naroff, chief economist at Naroff Economic Advisors in Holland, Pennsylvania. 

The jobs report added to data on consumer spending, the housing market and manufacturing in suggesting the economy continued to gain momentum in the fourth quarter after output rose at its fastest pace in two years in the third quarter.

About 226,000 people dropped out of the labor force last month. As a result, the labor participation rate, or the share of working-age Americans who are employed or at least looking for a job, fell 0.1 percentage point to 62.7 percent.

The participation rate is near multi-decade lows, partly reflecting demographic change. Economists believe that the low participation rate is hindering faster wage growth.

Job gains last month were broad, though manufacturing shed another 4,000 jobs. Manufacturing payrolls have now dropped for four straight months. Construction employment increased by 19,000 jobs last month after rising by 14,000 in October.

The retail sector shed 8,300 jobs in November, which could reflect a shift toward online shopping that has forced department stores such as Macy's Inc <M.N> to close several stores. Retail jobs have declined for two straight months.

Professional and business services payrolls increased by 63,000 last month. Healthcare and social assistance employment increased by 34,700. Temporary-help jobs, a harbinger for future hiring, rose by 14,300.

Government employment gained 22,000 jobs. There was a surge in local government hiring, which could have been driven by the Nov. 8 U.S. election.

(Reporting by Lucia Mutikani; Editing by Paul Simao)