The Chicago Tribune is a daily newspaper based in Chicago, Illinois, United States, owned by Tronc, Inc., formerly Tribune Publishing. Founded in 1847, and formerly self-styled as the "World's Greatest Newspaper" (for which WGN radio and television are named), it remains the most-read daily newspaper of the Chicago metropolitan area and the Great Lakes region. It is the eighth-largest newspaper in the United States by circulation (and became the second-largest under Tribune's ownership after the "Chicago Tribune"s parent company purchased the "Los Angeles Times"). 

Traditionally published as a broadsheet, on January 13, 2009, the "Tribune" announced it would continue publishing as a broadsheet for home delivery, but would publish in tabloid format for newsstand, news box, and commuter station sales. This change, however, proved to be unpopular with readers and in August 2011, the "Tribune" discontinued the tabloid edition, returning to its traditional broadsheet edition through all distribution channels. 

The "Tribune"s masthead is notable for displaying the American flag, in reference to the paper's motto, "An American Paper for Americans." The motto is no longer displayed on the masthead, where it was placed below the flag. 

The "Tribune" was founded by James Kelly, John E. Wheeler, and Joseph K. C. Forrest, publishing the first edition on June 10, 1847. Numerous changes in ownership and editorship took place over the next eight years. Initially, the "Tribune" was not politically affiliated, but tended to support either the Whig or Free Soil parties against the Democrats in elections. By late 1853, it was frequently running xenophobic editorials that criticized foreigners and Roman Catholics. About this time it also became a strong proponent of temperance. However nativist its editorials may have been, it was not until February 10, 1855 that the "Tribune" formally affiliated itself with the nativist American or Know Nothing party, whose candidate Levi Boone was elected Mayor of Chicago the following month.
when was the first edition published?
June 10, 1847