Expo '74 is notable as being the first world's fair with an environmental theme. It is also the fourth of five major world's fairs held in the Pacific Northwest (the others being 1905 Portland, 1909 Seattle, 1962 Seattle, and 1986 Vancouver). The majority of world's fairs since Expo '74 have had environmentalism as part of their themes.
This world's fair was particularly notable for its large participation by the Soviet Union, the first time since World War II that they participated in a United States world's fair. It would also be the last time.
Expo '74 was also the first world's fair held in the United States after the US formally joined the BIE.
Although not held in the Bicentennial year of 1976, Expo '74 was considered to be part of the Bicentennial celebration.