Arthur "Art" Matthew Longsjo Jr. (October 23, 1931 – September 16, 1958) was an American Olympian speed skater and cyclist.

He was the first American to compete in the Summer and Winter Olympics in the same year.

In 1954, he won the Quebec-Montreal Road Race and was named the Canadian Cyclist of the Year.

Longsjo was the first American to compete in both the Winter and Summer Olympics in the same year.

[6] Longsjo died in 1958 following a car accident in Burlington, Vermont.