WASHINGTON—New-home sales in the U.S. declined in April, posting the largest monthly drop since the end of last year and signaling the housing market is on weaker footing during the key spring selling season. Purchases of newly built single-family homes—a relatively narrow slice of all U.S. home sales—declined 6.9% to a seasonally adjusted annual rate of 673,000 in April, the Commerce Department said Thursday. This was the largest month-on-month drop since December of last year. Economists polled by The Wall Street Journal had expected a 2.7% drop. New-home sales declined in all regions but the Northeast, with purchases in the Midwest and West notching the biggest monthly drops since December 2018 too. Related Articles Still, the report offered positive signs for the housing market. The department revised up its estimate of overall new-home sales in March, and sales grew robustly in February and January. Meanwhile, sales were up 7% in April from …