Spring break here, and time for some less than crucial trivia.
Question: "What is the first rock and roll song?"
I don't say that the following is a perfect answer, or one that entirely meets the spirit of the question. I say only that given the facts, it is the most historically accurate answer:
The term "rock and roll" was invented by black Americans as a slang word for dancing and sex. The musical style that later became known as rock and roll was invented by black musicians by mixing influences from various genres (blues, jazz, country, folk, gospel, r ‘n’ b) in a way that involved only a slight variation on a number of earlier precursor songs from those genres.
Ike Turner's "Rocket 88" was the first recorded song to feature these variations. Recorded in early 1951 by Jackie Brenston and his Delta Cats, it featured Turner’s band under a different name with Brenston singing. Brenston received the song writing credits although the tune was probably primarily Turner’s.
However, at the time that song was made, it wasn’t called "rock and roll." As far as the historical record notes, Alan Freed was the first to use the term "rock and roll" to identify the style of music as a genre. Freed promoted the concept for what is considered the first rock and roll concert on August 21, 1952 at the “Moondog Coronation Ball” held at the Cleveland Arena.
Bill Haley, with songs like "Rock Around The Clock," was the first musician to consciously present his music as something called rock and roll, although the songs themselves were relatively pale translations of the more powerful music being made by black musicians. Still, many white people considered rock and roll to be black music and condemned it as such, especially after Elvis Presley's first singles, which is ironic but not surprising given that Presley showed that white people could play excellent music in that style.
Therefore, identifying the first rock and roll song is only partly a question of historical fact. It’s also a question of culture and value. If you say that it's crucial to note the first appearance of the style, even if no one at the time thought they were hearing rock and roll, then "Rocket 88" seems the answer, an answer which has the further value of not denying the centrality of African American culture to rock and roll. But if you answer the question by saying that the issue is the first record that people thought, at the time, was rock and roll, then the answer is Haley’s 1952 release “Rock The Joint,” a minor hit.