Few genres of music have had more of an impact of modern musical styles than The Blues, a style of music which developed in the Reconstruction era Southern United States out of gospel, folk, and the work songs sung on American slave plantations. The pain, and misery that permeates the genre is nonetheless uplifting, and resulted in a mixture of European, and African scales, and rhythms that has shaped modern country, rock, R&B, funk, jazz, amongst other styles.
Lyrically, the style often used the trope of a lost love, racial tension, and poverty. Harmonically European, with the addition of a "blue note", which likely a vestigial piece of a West African harmonic structure.
This note, is what provides the "soulful" feeling to the music, and separates it from other forms of Western music, which tend to rely heavily on scales that are more rigid. This is what makes most American music sound, well, American. Name a prominent western musician from the last 50 years, and there's going to be an example of them using this kind of scale.
Throughout the 1930s, 40s, and early 50s Blues, and Jazz began to grow. This era was fueled by big names such as Charlie Christian, B.B. King, Albert King, Muddy Waters, Son House, among many others. These black artists were all labelled as Blues by record labels of the era, whilst their white contemporaries, like Jimmy Rodgers, and Hank Williams were called Country. This created a false dichotomy as it meant that despite the harmonic structure being near identical, the genres were separated on the basis of the skin colour of the performers.
Eventually this would mean many Black American Blues artists not receiving the attention many of them were due, and the genre was almost entirely eclipsed by Rock n Roll, country, and surf music in the late 1950s. All that saved the genre was the interest of a few young men at the time in the post-war United Kingdom. Unlike the United States, and Canada, Britain was absolutely decimated during the Second World War, resulting in many young people born during the war growing up not knowing a world without craters in the street, and surrounded by mountains of rubble. Some of these young people got a hold of American blues records, and fell in love. Some of these young people included Mick Jagger, Eric Clapton, John Lennon, Roger Daltrey, and Jimmy Page.
These young British artists took the Blues, and supercharged it throughout the 1960s, resulting in what we now know as rock music. They would even take the black American blues artists on tour with them, meaning a resurgence in popularity that saved many of their careers. One such act that toured with the Rolling Stones, were Ike and Tina Turner. The same Tina Turner who was a massive R&B hit maker in the 1980s.
The reintroduction of the Blues into the pop lexicon was a necessary, and instrumental step in reinvigorating American pop music, even if it came through a European messenger. The end of the civil rights fight in the United States would also mean that white, and black Americans no longer had to be categorised by race. If a black man wanted to sing country, he could, and if a white man liked singing the blues or R&B that was fine, and dandy. But the pain, and sorrow that has permeated the style since the beginning still does. The pain is something that we can all understand, regardless of race, religion, or background.
When one hears Eric Clapton, Gary Clarke jr, or Freddie King playing guitar or singing, one doesn't hear the artist's race, the listener hears the emotions that the other person is feeling, and sympathises. That is the true power of the Blues, and that is what makes the style so important. When you hear a person singing about how their lover hurt them, or how they're so glad about something, you understand, and it makes you feel the same way. That is the true power of music, it can unite people in emotion if it is used the right way, and in my opinion, the blues does this better than any other kind of music.
Here's Eric to prove the point in a way words can't: