There's a lot of talk about Ragtime music, but the tunes played in this film are New Orleans blues, Dixieland jazz, and Big Band jazz. Ragtime is like the Scott Joplin music heard in The Sting (1973). There's nothing like that in this movie.
Far from the city government clearing away Storyville because it didn't like jazz or drinking or kissing in the streets, it did so at the behest of the Navy. It is only hinted at in the movie, but Storyville was dense with brothels, including child brothels, and the Navy did not want such a blatant temptation to men in wartime.
In the first scene there is a shot of Basin Street, and the year 1917. We hear West End Blues playing, which was not recorded until 1928.
The Billboard magazine cover shown is from 1946 while the film story is taking place around 1918.
While some of the costumes are authentic to the period (1918), others are blatantly not, such as the strapless chiffon evening gown worn by Nick's old girlfriend. Also, women would have worn their hair up, not loose and down to their shoulders.