"The "Blue Note" has represented St. Louis’ NHL team since its inception in 1967, with some alterations along the way. It’s a symbol that stands not just for the team, but the city and region, which is renowned for its history of jazz and blues music. The color blue is an obvious fit with the name and is accentuated with a yellow that used to take up more space on the logo."
https://sportslogohistory.com/st-louis-blues-primary-logo