On a humid night in New Orleans, there’s little finer than sitting on a worn curb in the greasy Vieux Carre, sipping a drink and listening to the sounds that leak out of nearby windows. Bourbon Street has its own soundtrack. It’s easy to bring it to mind: wailing clarinets and trumpets, rollicking drum kit rhythms, string bass, banjo strumming and plenty of brass. In the Vieux Carre, that sound is in the air, all around, and it’s often courtesy of Preservation Hall.

That venerable institution is ground zero for old-school jazz, that distinctly New Orleanian brew that’s changed little since it first arrived almost a century ago. The moniker is not accidental; Preservation Hall exists precisely in order to preserve New Orleans jazz as it existed before jazz splintered and evolved into things like bebop and free jazz.

As musical forms go, New Orleans jazz is an easy one to preserve, because it’s so appealing even if you don’t necessarily care about its intricacies. Unlike most contemporary jazz, it often has vocals, offering an easy hook. Such wonderfully listenable stuff argues eloquently for itself.

Still, one of the hallmarks of the style challenges listeners, but in a way so painless few notice. It’s common to have two or even three soloists wailing away, careening around each other while the tuba blows and the drums propel the tune. Those sounds meld together to create a sense of wild abandon that’s an ingrained part of New Orleans’ identity. Listen closely to those solos, however, and you can switch between following one line and another, maybe even return to hearing the overall effect while still following the contours of the melodies. Once you start listening that way, it’s hard to get enough. Many of the chord structures and song forms are familiar, and most are less complex than later jazz, but make no mistake: this is sophisticated music, the bedrock of all that has followed in the increasingly esoteric world of jazz. It was, after all, in New Orleans that one of the most important figures in all of jazz, Louis Armstrong, got his start.

Preservation Hall itself has a history that reveals much about the culture and political climate of the Crescent City. It is, in many ways, a culture so different from that of the rest of America it might as well be on Mars. There’s nowhere else you can find such a load of unlikely things in combination, things like “king cakes,” in which a plastic baby Jesus is hidden; Mardi Gras krewes; above-ground graves of revered voodoo queens; and unique French/Creole/Southern cuisine. It’s also a city in which races mixed to an unprecedented degree, dogged all the while by an intricate system of class and moniker to keep track of that mixing. Though it’s almost alien in many ways, New Orleans is still surrounded by the Deep South.

These days, when tourists from all over the world pack into the surprisingly small, un-air-conditioned swelter of Preservation Hall, it’s easy to miss that the place flew in the face of Southern racial attitudes from its beginning in the late ’50s and early ’60s; that it was run by Northern entrepreneurs (Allan and Sandra Jaffe) who loved the music didn’t help. The traditional sounds of New Orleans were the raison d’etre of Preservation Hall, and making music had already long been central to dissolving race barriers. But conservative whites weren’t necessarily on board.

According to the liner notes on a spectacular new box set of recordings from 50 years of the Hall’s existence, the impetus for founding the venue was a series of sessions organized by gallery owner Larry Borenstein in the late ’50s. The racial mixing that happened among those musicians attracted the attention of authorities, and, Borenstein shared in a 1968 book about Preservation Hall, attitudes hardly proved flexible. Trumpeter Kid Thomas Valentine was arrested, and the judge, said Borenstein, told Valentine, “We don’t want Yankees coming to New Orleans mixing cream with our coffee,” and let him go on the promise that he wouldn’t get “uppity” again.

In that climate, Preservation Hall carried the torch for music that ignored such barriers.

For the whole scope of its history, the term “Preservation Hall Jazz Band” has been far from exact. Visit the Hall any given night, and you’ll find performers of many ages playing traditional New Orleans music. They’re almost inevitably some of the best players the city has to offer. Go the next night, and the bandstand might be occupied by a very different crew of players. The level of musicianship and the well of songs, however, will remain the same. The “Band” is more an idea than a consistent lineup, and many a variant of the lineup has toured the world since Preservation Hall’s 1961 founding.

The new box set, the 50th Anniversary Collection, offers recordings from the entire run of the Hall so far, and jams music from the earliest years right up against modern takes. There is a great continuity in the music, proof that the “preservation” aspect is working well, and there’s also ample evidence of evolution in more recent years. That’s because Ben Jaffe, the current director of the Hall, has cultivated innovation as well as tradition, pushing the players to incorporate new material and record with guests from outside the tradition. The box set contains two particular highlights of that approach, one with Pete Seeger, the other with Tom Waits, who screams out a fascinating rendition of an old Mardi Gras chant called “Tootie Ma is a Big Fine Thing.”

This week, the current touring version of the Preservation Hall Jazz Band is slated to blow the doors off the Clark Art Institute in Williamstown. It may not be nearly so sweaty as Preservation Hall, but the music is bound to be just as hot.•

LATE BREAKING INFO: because of the approaching snowstorm, the PHJB appearance has been cancelled.

Feb. 8, 8 pm., $38-45, Sterling and Francine Clark Art Institute, 225 South St., Williamstown. Three-course dinner preceding concert at 6 p.m.: $27 (does not include beverage, tax, or gratuity), reservations required. (413) 458-0524, clarkart.edu.