Planners of San Francisco’s 1915 Panama-Pacific International Exposition wanted to present their city as the center of an American empire that stretched from Maine to the Philippines. The fair’s head landscape engineer John McLaren and his team spent three years planning and planting the fairgrounds to reinforce this message. They used plants and flowers from around the world to show off California’s gentle climate, and convey to visitors the idea that the city was at the center of the commercial world. This article details the work that McLaren’s crews undertook, analyzes three sections of the fairgrounds, and discusses the impact the fair’s landscaping made on visitors.