Here's an excerpt of the Wikipedia article on Sam and Dave and the song "Soul Man":

"Samuel David Moore (b. October 12, 1935, Miami, Florida), David Prater (b. May 9, 1937, Ocilla, Georgia,- d. April 9, 1988 Sycamore, Georgia), are American Soul and Rhythm & Blues (R&B) singers who were members of the soul vocal duo Sam & Dave. They recorded and performed together from 1961 through 1981; Sam Moore was the tenor (higher) vocalist and Dave Prater was the baritone/tenor (lower) vocalist...

Sam & Dave enjoyed significant commercial success as recording artists and performers from the mid to late 1960s, including 10 consecutive Top 20 Billboard R&B singles from 1966 to 1968 and 14 R &B chart appearances overall, and 16 appearances on the Billboard US Pop music charts overall. Their streak of consecutive top 20 songs outperformed James Brown, Otis Redding, Wilson Pickett and all other R&B artists except for Aretha Franklin from 1966-1968. They had the #1 Billboard R&B single for the year for 1966 - "Hold On, I'm Comin'", and the #2 R&B single for the year in 1967 with "Soul Man". Both "Soul Man"(1967) and "Hold On, I'm Comin'" (1966)also reached the number 1 position as R&B singles during the year they were released, and they had Pop crossover hits with Soul Man (#2 Pop, #1 Cashbox), "I Thank You"(#9 Pop), and "Hold On, I'm Comin'"(#21 Pop). "Soul Man" was on the R&B charts for a remarkable 18 weeks(longer than ANY other #1 R&B song from 1966-1969)and spent an equally remarkable 7 weeks at #1, and was ranked the #13 most successful R&B hit of the entire 1960's by Joel Whitburn's "Top R&B/Hip Hop Singles Guide". Both "Soul Man" and "Hold On, I'm Comin" have been voted on greatest song lists in Rolling Stone Magazine,[4] and "Soul Man" was voted into the Grammy Hall of Fame, which was established to honor truly timeless recordings. "Soul Man" was also named in 2007 as one of the "500 Songs that Shaped Rock & Roll" by the Rock and Roll Hall of Fame. "Soul Man" was also honored by the RIAA as one of the "Songs of the Century" for the 20th Century. The Album "Hold On, I'm Comin" reached the #1 position during its 19 weeks on the Billboard R&B charts in 1966, and was an RIAA certified Gold album"...

http://en.wikipedia.org/wiki/Sam_&_Dave