Detail from the official design guidelines.
The Expo 74 logo was designed by Spokane's own Lloyd L. Carlson of the advertising firm Devine Miller Carlson & Donaldson. Carlson had previously designed the city's seal in 1966.
Although straightforward in appearance, there is significant thought and nuance underlying each choice in this design. The overall shape is based on the Möbius strip, a shape "with no definable beginning or end," intended to evoke humankind's ongoing relationship with the environment and the concept of recycling. This choice also ties into Expo ‘74’s environmental themes in its resemblance to the universal recycling symbol, which was also based on the Möbius strip and had been introduced at the first Earth Day celebration in 1972.
The three colors used in the logo represent multiple concepts significant to the fair: "This is where the selected colours of white, blue, and green are also significant. When viewed through the context of ‘man’s environment,’ they represent cleanliness of fresh air; purity of clean water; and unspoiled natural beauty of plants and trees, respectively. Within the context of “play in harmony”, each unit represents a form of recreation: (white) winter sports, (blue) water sports, and (green) summer outdoor recreation on land. Finally, considering the theme of “living in harmony,” the units represent keeping rivers and streams pollution free; maintaining fresh air; and finding solutions to industrial pollution problems." (Quote from LogoHistories.com.)
According to the official design document, the green in the Expo '74 logo must always be on the left. The exact shade of chartreuse green used is Pantone 382, RGB 196/214/0, and HEX C4D600. The aqua blue is Pantone 312, RGB 0/169/206, and HEX 00A9CE. (Color code conversions performed using this site.) Vendors using the Expo logo were expected to use white ink to print the white section of the logo, while the inner triangle was intended to show the underlying color of the item. In practice, this did not always happen.
Not only did the logo appear on a multitude of items, but its shape - a hexagon with rounded corners - was echoed all over the design of the fair. This repeated silhouette provided visual continuity within the fair’s materials. It also evoked the natural geometry of honeycomb, an apt allusion for this environmentally-oriented fair.
The year after Expo, Carlson's city seal design and his Expo logo were combined into the city's official flag. This design served as the flag of the city of Spokane from 1975 to 2021.
