Divided back postcard showing the Union Oil Company of California exhibit at the 1915–1916 Panama–California International Exposition in San Diego. The display features ornate classical-style columns framing a central industrial presentation with oil barrels, product models, and Union Oil branding throughout. A striking example of early corporate advertising blended with exposition-era architecture and decorative presentation. Strong appeal for collectors of California history, world’s fairs, petroleum industry memorabilia, and early advertising postcards.