The United States has not yet won any gold medals in Beijing.

As of Tuesday, 31 gold medals had been awarded at the Winter Olympics, with Sweden picking up four of them to lead the pack. The United States has yet to win any golds, earning only one bronze and four silver medals so far.

What gives?

Only twice before has the United States reached at least the fifth day of a Winter Games before picking up a gold medal, said Bill Mallon, a leading authority on Olympic history. The first time was the 1984 Games in Sarajevo, Yugoslavia, when the skier Debbie Armstrong won gold in the women’s slalom.

The second time the United States had not won a gold medal by the fifth day was at the 1988 Calgary Games. It wasn’t until the figure skater Brian Boitano placed first in the men’s competition, defeating the world champion Brian Orser of Canada, that the United States won gold that year.

“I guess we would have expected possibly one gold by now, but we haven’t had a lot of strong events,” Mallon said, adding that the American skier Mikaela Shiffrin was the strongest gold medal contender to date in Beijing.

But on Monday, Shiffrin fell and was disqualified from the giant slalom event.

The most likely gold medalist remaining is Chloe Kim, the snowboarder and defending champion in the women’s halfpipe competition, which starts Wednesday.

According to Mallon, at virtually every Olympics, the United States has won at least one of each of the three types of medal, with two exceptions: It failed to win a bronze medal at the 1984 Sarajevo Games and did not capture a silver at the 1936 Games in Garmisch-Partenkirchen, Germany.