The Union Leagues were quasi-secretive men’s clubs established during the American Civil War (1861–1865) to promote loyalty to the Union of the United States of America, the policies of newly elected 16th President Abraham Lincoln (1809–1865, served 1861–1865), and to combat what they believed to be the treasonous words and actions of anti-war, anti-black "Copperhead" Democrats. Though initially nonpartisan, by the war's last year they were in open alliance with the Republican Party, pro-Union Democrats, and the Union military. The most famous of these clubs were formed in Philadelphia, New York, and Boston and were composed of prosperous men who raised money for war-related service organizations, such as the United States Sanitary Commission, which provided medical care to treat Federal soldiers wounded in battle at a time when the military was ill-prepared for the scale of need. The clubs supported the Republican Party with funding, organizational support, and activism. Union Leagues also existed throughout the land which were created primarily by working-class men. By the spring of 1863, these disparate councils were organized under the Union League of America (ULA) organization which was headquartered in Washington, D.C. Like-minded organizations aimed at the working class, which became known as Loyal Leagues, were also created in New York. Similar patriotic organizations also existed for women and were known as Ladies Union Leagues.
In December 1862, the Union League of Philadelphia was the first of the elite eastern Leagues to be established, though the first ULA council had formed in Pekin, Illinois in the summer of 1862. The famous Union League of Philadelphia building on Broad Street in center city Philadelphia, south of City Hall was built in 1865, and is designed in the Victorian style. It is still active, as are the Union League Clubs of New York and Chicago. Membership in the league is selective, and is comparable in social status to membership in a country club. Union League buildings often serve as private social clubs, with areas devoted to drinking establishments, meetings, lectures, libraries, dinners/banquets, speeches/addresses, socializing and relaxing, etc.
During the Reconstruction era, Union Leagues were formed across the South after 1867 as working auxiliaries of the Republican Party, supported entirely by Northern interests. They were secret organizations that mobilized freedmen to register to vote and to vote Republican. They taught freedmen Union views on political issues and which way to vote on them, and promoted civic projects. Eric Foner reports:
By the end of 1867 it seemed that virtually every black voter in the South had enrolled in the Union League, the Loyal League, or some equivalent local political organization. Meetings were generally held in a black church or school.
The Ku Klux Klan, a secret alliance of white supremacists that opposed civil rights and terrorized leaders of the African American community and African American voters, sometimes assassinated Union League leadership.
After the Civil War, members of the Union League Club of New York broadened their support of other philanthropic purposes. For instance, they helped to found the Metropolitan Museum of Art, and funded construction of the Statue of Liberty's pedestal and Grant's Tomb.
Some former Union League buildings have been adapted for other uses; for instance, in Brooklyn, New York, the former Union League Club building now serves as a senior citizens' home. The former Union League building in New Haven, Connecticut is used as a restaurant.
In the post-World War II period, members of the Union League Club of Chicago raised contributions to found the Union League Civic and Arts Foundation in 1949 as a public, not-for-profit charitable and educational organization. The Foundation's mission is one of community enrichment.
Members of the League in Philadelphia include Cyrus McCormick, Robert Todd Lincoln, Adolph E. Borie, Daniel Burnham, William D. Boyce, Charles D. Barney, and George J. Smith.