HemisFair '68 was the first officially designated world's fair

World's Fair

World's fair, World fair, Universal Exposition, and World Expo are various large public exhibitions held in different parts of the world. The first Expo was held in The Crystal Palace in Hyde Park, London, United Kingdom, in 1851, under the title "Great Exhibition of the Works of Industry of All...

 (or international exposition) held in the southwestern United States

Southwestern United States

The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...

. San Antonio, Texas

San Antonio, Texas

San Antonio is the seventh-largest city in the United States of America and the second-largest city within the state of Texas, with a population of 1.33 million. Located in the American Southwest and the south–central part of Texas, the city serves as the seat of Bexar County. In 2011,...

 hosted the fair from April 6 through October 6, 1968. More than thirty nations hosted pavilions

Pavilion (structure)

In architecture a pavilion has two main meanings.-Free-standing structure:Pavilion may refer to a free-standing structure sited a short distance from a main residence, whose architecture makes it an object of pleasure. Large or small, there is usually a connection with relaxation and pleasure in...

 at the fair. The fair was held in conjunction with the 250th anniversary of the founding of San Antonio. The theme of the fair was "The Confluence of Civilizations in the Americas." The official world's fair sanctioning body, the Bureau International des Expositions (BIE) accredited HemisFair '68 on November 17, 1965.
The venture, which had an announced cost of $156 million, was financed by a combination of public and private funds.