The 19th Regiment Illinois Volunteer Infantry was an infantry regiment that served in the Union Army during the American Civil War. Three companies formerly with Col. Elmer Ellsworth's Zouave Cadets wore a zouave uniform consisting of a dark blue zouave jacket with red trimmings, red pants, leather gaiters, a sky blue shirt, red sash, and a red French styled kepi with a dark blue band. The jacket cuffs were trimmed in yellow-orange and red. Brass buttons went down both fronts of the jacket. They were organized into four separate companies on May 4, 1861 in Chicago. It was consolidated and mustered into Federal service as the 19th Illinois Volunteer Infantry on June 17, 1861. It was mustered out at Chicago on July 9, 1864.