To start, the sousaphone was created by the critically-acclaimed bandleader John Philip Sousa after wanting to make instruments that were both easier to carry than concert-style tubas and were higher to push their deep tones further to better accommodate a marching band. To get his desired result, he consulted a man by the name of J.W. Pepper to construct the instrument in 1893. Due to the innovative design that allowed the heavy brass wind instrument to be worn instead of carried, it spread widely in not only Sousa’s works, but in every marching band to this day. 

The reasons that the word “sousaphone” has been replaced with “tuba” is mostly to shorten the name and describe its ability to sound just like a tuba since they are like each other. Both the tuba and the sousaphone are low-pitched, brass instruments that are typically played in groups. Due to the similarities they share, both instruments are colloquially called a “tuba.”