The Union League of Philadelphia is a private club founded in 1862 by the Old Philadelphians as a patriotic society to support the policies of Abraham Lincoln. As of 2022, the club has over 4,000 members. Its main building was built in 1865 and added to the National Register of Historic Places in 1979. Union League clubs, which are legally separate but share similar histories and maintain reciprocal links with one another, are also located in Chicago and New York City. Additional Union League clubs were formerly located in Brooklyn, New York and New Haven, Connecticut.