The Union Leagues were quasi-secretive men's clubs established separately, starting in 1862, and continuing throughout the Civil War (1861–1865). The oldest Union League of America council member, an organization originally called "The League of Union Men", was formed in June 1862 in Pekin, Illinois. Four months later, on November 22, 1862, the Union League of Philadelphia, the first of the elite eastern Leagues and the second oldest ULA council member, was established (and is still active today, as are the Union League Clubs of New York and Chicago).
The Union Leagues were established to promote loyalty to the Union of the United States of America, to support the policies of newly elected 16th President Abraham Lincoln (1809–1865, served 1861–1865) and to assure his reelection in 1864, 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 election year of 1864 they were in open alliance with the Republican Party, supporting the reelection of Abraham Lincoln, but were also supportive of pro-Union Democrats.
The largest and best known of these clubs formed in Philadelphia, New York, and Boston, 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.
At the same time as these elite clubs were formed, Union Leagues sprang-up throughout the rest of the North, created primarily by working-class men, while women's organizations known as Ladies Union Leagues appeared in towns across the North. In the spring of 1863 these separate, though (mostly) philosophically aligned groups, were organized under the Union League of America (ULA), headquartered in Washington, D.C.