Expo '74, officially known as the International Exposition on the Environment, Spokane 1974, was a world's fair held May 4, 1974, to November 3, 1974 in Spokane, Washington in the northwest United States. It was the first environmentally themed world's fair and attended by roughly 5.6 million people. The heart of the fair park grounds was located on Canada Island, Havermale Island, and the adjacent south bank of the Spokane River, comprising present-day Riverfront Park, in the center of the city.