Demand for new homes in the United States made its biggest jump in nearly four years during August, but the level of sales in three prior months was revised lower.

New single-family home sales rose 9.4% to a seasonally adjusted annual rate of 1.184 million, the Commerce Department said today. The increase was the largest since sales shot up 11.7% in December 2000. Economists had predicted sales would climb 1.4% to a 1.150 million annual rate.

July home sales fell 7.3% as the government lowered the annual rate to 1.082 million from an earlier estimated 1.134 million. June sales were revised downward to 1.167 million from an earlier estimated 1.211 million. Sales in May were lowered to 1.244 million from an initially estimated 1.283 million.

The average 30-year mortgage rate slipped below the 6% mark in early August, according to data from Freddie Mac. Shorter-term rates also eased down.

While new-home demand rose amid dropping mortgages rates, sales of existing homes last month declined. The National Association of Realtors reported on Friday that resales slipped 2.7% to a 6.54 million annual rate from July’s 6.72 million.