WASHINGTON, Jan. 26 (Xinhua) -- The U.S. economy grew 2.6 percent in the fourth quarter of 2017, lower than the 3.2 percent in the previous quarter, the Commerce Department said Friday.

Consumer spending, accounting for more than two thirds of the economy, remained the major growth engine. Consumption grew 3.8 percent in the quarter, the fastest growth in three years.

It contributed 2.58 percentage points to the growth in the fourth quarter, compared to 1.49 percentage points in the third quarter.

Private inventory investment slowed in the fourth quarter, which subtracted 0.67 percentage point from the economic growth.

With a strong domestic demand, imports increased at their fastest rate in more than seven years, with a surge of 13.9 percent. Net exports also subtracted 1.13 percentage points from the GDP growth.

For the whole of 2017, the economy expanded at a solid pace of 2.3 percent, higher than the 1.5 percent increase in 2016, but below market expectations of 2.5 percent.

The expansion, which began from mid-2009, is the third longest in American history. But it has remained at a modest pace, slower than previous expansion cycles.

With the passage of the tax cut bill last year, economists widely expected the economy would continue steady growth this year.

William Dudley, president of the New York Federal Reserve Bank, recently raised his forecast for U.S. growth in 2018 by 0.5 to 0.75 percentage point to a range from 2.5 percent to 2.75 percent.

"About one-third of this upward revision reflects the firmer momentum of the economy going into 2018 and about two-thirds the stimulative impact of the tax legislation," Dudley said.

Friday's GDP report was the preliminary estimate. The Commerce Department is scheduled to release revised statistics in February, based on more complete data.