Also in 1948, Aristocrat issued Robert Nighthawk's "My Sweet Lovin' Woman," which introduced Willie Dixon to the fold; the brothers bought out Aron two years later, rechristening the company Chess Records at that time. Their first release under the new banner, Gene Ammons' "My Foolish Heart," was quickly followed by Waters' seminal "Rollin' Stone." Local guitarist Jimmy Rogers was signed to the label around the same time, debuting with "That's All Right" and remaining a label fixture throughout the decade thanks to singles like "Sloppy Drunk," "You're the One," and "Walking by Myself." However, the most important addition of 1950 was Waters' harpist Little Walter, who within two years topped the R&B charts with his solo instrumental hit "Juke" and went on to score smashes like "Mean Old World," "You're So Fine," and "My Babe," in the process revolutionizing the role of blues harmonica with his pioneering amplified style.

All told, the success of the label's artists established Chess as the cutting-edge in urban blues; Leonard soon began seeking talent outside of the Chicago area, contacting Sun Records' Sam Phillips to aid in the search. Phillips sent Chess masters of recordings by Rufus Thomas, Dr. Isaiah Ross, and Bobby Bland; his key discovery, however, was Howlin' Wolf, who scored a major hit in 1951 with his label debut "How Many More Years." He relocated from Memphis to Chicago in 1953, soon recording classic tracks like "Smokestack Lightnin'" and "Who Will Be Next." By the mid-'50s, Chess Records included affiliated labels Checker, Argo, and Specialist, with new signings ranging from legends like Sonny Boy Williamson (Rice Miller), who quickly struck paydirt with "Don't Start Me to Talkin'," to newcomers like Bo Diddley, whose debut single -- the two-sided hit "Bo Diddley"/"I'm a Man" -- introduced one of rock & roll's most influential and enduring beats.

Still, Leonard's most important discovery of the period was Chuck Berry, who signed to Chess in mid-1955. From his first hit "Maybellene" onward, Berry essentially wrote the book on rock & roll, creating its most indelible guitar riffs over the course of singles like "Johnny B. Goode" and "Sweet Little Sixteen." Hits from the Moonglows and the Flamingos also brought Chess success on the pop charts, and the label continued issuing classic blues as well, welcoming artists like Buddy Guy, Otis Rush, and Etta James to the roster by 1960. Other performers like Fontella Bass, Laura Lee, Koko Taylor, Little Milton, and Tommy Tucker continued Chess' hit streak in the years to follow, while the British R&B boom of the early '60s illuminated the label's massive influence for a new generation of listeners. However, the death of Leonard Chess on October 16, 1969 proved a dagger in the heart of the company, and the Chess name and logo then passed through many hands before MCA began a major reissue program during the '90s.