The Centennial Exposition is opened in Philadelphia.

The Centennial International Exhibition, officially the International Exhibition of Arts, Manufactures, and Products of the Soil and Mine, was held in Philadelphia, Pennsylvania, from May 10 to November 10, 1876. It was the first official world's fair to be held in the United States and coincided with the centennial anniversary of the Declaration of Independence's adoption in Philadelphia on July 4, 1776.

Philadelphia, colloquially referred to as Philly, is the most populous city in the U.S. state of Pennsylvania. It is the sixth-most populous city in the United States with a population of 1.6 million at the 2020 census, while the Philadelphia metropolitan area with 6.33 million residents is the nation's ninth-largest metropolitan area. Philadelphia is known for its culture, cuisine, and history, maintaining contemporary influence in business and industry, culture, sports, and music.

May 10 is the 130th day of the year in the Gregorian calendar; 235 days remain until the end of the year.