WASHINGTON — U.S. sales of newly built homes fell 0.4 percent in December, cooling slightly after low mortgage rates fueled gains for much of 2019.

The Commerce Department said Monday that new single-family houses sold at a seasonally adjusted annual rate of 694,000 last month. But for all of 2019, sales climbed 10.3 percent to 681,000, the highest total since 2007 when 776,000 new homes were sold as the housing bubble was beginning to deflate ahead of the Great Recession.

Last year’s gains were driven entirely by new homes purchased in the South and West. Sales of new homes slumped in the Northeast and Midwest in 2019.

Lower mortgage rates began to boost real estate sales relative to 2018. December’s median new-home sales price was $331,400, up 0.5 percent from a year ago.