The New York City music scene of the late 1980's and early 1990's is inevitably referred to as a "family" by anyone who played there or saw a show by any of the various up-and-coming bands of the era. From local bands God Street Wine, Joan Osborne and Jono Manson to touring bands Widespread Panic, Phish, Aquarium Rescue Unit and others, they all knew and respected each other, and cross-pollination ran rampant at their shows. However, the two bands most frequently associated with one another were Blues Traveler and the Spin Doctors. The two would play the same local bars on the same schedule, often hitting the same venues on different days within the same week. Blues Traveler landed a regular gig at the Wetlands Preserve while the Spin Doctors held down a spot at Nightingale's. In a 1998 interview, Chan Kinchla, when asked about the shows, remembered them fondly. "We used to play the same places near each other and the crowd would go back and forth when one band's set ended. One time one of us ran down to the Spin Doctors' gig and played with them, and it eventually got to the point where one night we'd all go there, take their places one by one, and then they'd go back to where we had been playing and end up playing there for the rest of the night! Eventually we started booking gigs together and playing that way."
While this may have been a common occurrence in the years preceding it, May 26th, 1990 is the first recorded full-band segue between the two bands. On the date in question, the two bands shared a bill at the Marquee in New York City. The Spin Doctors began their set with Turn It Upside Down, played six songs, and then launched into a lengthy Shinbone Alley>Forty or Fifty segue. In mid-song, members of Blues Traveler began joining the Spin Doctors crew on stage and turning the song into a double-band jam. As the groove continued, Spin Doctors members began leaving the stage, and gradually the laid-back Forty or Fifty slowly morphed into the head-on rush of Trust in Trust. The jam ended two songs later, after a high-speed Crash Burn>Wouldn't It Make You Mad?, and the music never stopped. Amazingly, the two bands traded three more sets this way, segueing from Blues Traveler back to the Spin Doctors and back to Blues Traveler again, encoring with a raucous eight-person take on Johnny B. Goode. Such shows apparently occurred up through a 1994 tour which took both bands to the United Kingdom, but with the decline of the Spin Doctors and the outward-looking tour schedule of both bands, such shows have now disappeared from both bands' radar.
More about the Spinning Traveler phenomenon can be found in this quote from the Official FAQ:
Much can be said about the relationship between BT and the Spin Doctors. Many rumors abound and much hullabaloo has been made over the weird pupa-like state in a show involving the two bands . What this is really all about involves the truest singular connection between them and that is the musical one. Both bands having known each other for so long as well as having mastered the art of segueing one song into the next had naturally taken the next logical step segueing into each other. For example, the Spin Doctors will be playing Shinbone Alley, as the jam progresses, John Popper comes out and starts soloing and trading riffs with Mr. Schenkman. Then Chan Kinchla will come on stage as the jam starts to take on eclectic possibilities. Soon Bob Sheehan will comes out and trade bass tones with Marc White. As this is happening, Brendan Hill will start tinging and pinging Aaron Comess' cymbals. The key of this jam may shift at this point as needed, and at some point no one knows exactly where, Brendan is now sitting down and it is Aaron Comess who is tinging and pinging. Once he leaves, the groove is decidedly different, everyone's still going at full blast. As member of Spin Doctors leave the stage, it is becoming apparent that this jam is sounding more and more like But Anyway. Before you know it, BT finishes up But Anyway and are now well into their set. If you go to the bathroom, or even look down for a minute, you could miss it and many are the strange reports from fans who swear they were watching the Spin Doctors only realize they had been dancing to BT the whole time. This effect can cause not only disorientation, but a nervous, queasy feeling for those unprepared. A feeling that perhaps they aren't really who they were to begin with, but someone else entirely, and that they had been this person for most of their life, only now realizing that their parents had given birth to, and raised someone else. Be careful, when at these shows to accept who you actually are because you cannot sue yourself, though many have tried. It doesn't matter that much now because the bands have grown so differently from those special days that you probably can relax in relative comfort, confident that you weren't that guy standing next to you. Whether that is a good thing or a bad thing, is up to you.