Originally, the sport of cross-country skiing was simply one half of the Nordic combined event made popular by the Norwegian ski festivals of the late 1800s.
Separate cross-country-only competitions gained popularity quickly, and two men's events were included at the first Winter Olympic Games in 1924. Cross-country skiing is one of seven winter sports that have been contested at every Winter Games.
The first women's cross-country event, however, was not added until the 1952 Games in Oslo, Norway.
There are two styles of cross-country skiing at the Olympics.
The sprint competition is a single-elimination tournament that begins with 16 skiers grouped into four heats. The top two finishers in each heat advance. The process is repeated until there are four semifinalists competing for the three medals.
The combined pursuit is a classical race followed by a freestyle race.
The mass start event was introduced at the Salt Lake City 2002 Olympic Winter Games. Skiers start simultaneously, lined up in an arrow format, with the best-ranked skiers positioned at the arrow's point. The women's event is 30 km and the men's event is 50 km. The first athlete across the line wins. It is not uncommon for 10 skiers to be fighting for the line, often resulting in a photo finish.
The relay is similar to those run in track and field. Except instead of passing a baton, skiers must simply touch their teammate with their hand to initiate the next leg.
Until 2006, the United States' lone cross-country medal was a silver won by Bill Koch in 1976. U.S. skiers took home two golds and a bronze in the 2006 Torino Winter Games.