The list of official participants in this year’s fifth edition of Upstate Art Weekend, a sprawling festival that embraces nearly every art event or exhibition happening north of New York City over the next four days, has reached 145. It’s a dramatic rise from an informal band of some two dozen arts centers and galleries just four years ago, and it now spans 10 counties in New York State.

While the participants include perpetually open historical sites like Boscobel and Olana, and also a few aesthetically inclined specialty grocers and clothing designers, most of the exhibits really are up just for the occasion, and many include one-off performances, like Audra Wolowiec’s choral performance on a boat crossing the Hudson.

Some events spill over from last year, but there are many new developments. The New Art Dealers Alliance, which put on a small fair last year at the Foreland complex in Catskill, N.Y., is taking the year off, but Foreland is hosting its own youth arts fund-raiser, with auctions, ceramics, food and a conceptual sound installation. At the Zero Art Fair in Elizaville, nearby, visitors are welcome to take home one available work per day for free under an innovative contract that vests ownership over five years, after which time title will pass to the new owner. The contract was developed for the artist William Powhida (who founded that fair with the artist Jennifer Dalton).

If what you really yearn for is that overwhelming art fair feeling, and scene, be sure to visit The Campus, in Claverack, outside Hudson, N.Y. There, in a 78,000-square-foot former school building unused for decades, six New York galleries have combined forces with the curator Timo Kappeller to mount an 80-plus-artist show that fills classroom after unrenovated classroom and spreads out onto 22 acres. (The six galleries — Bortolami, James Cohan, Kaufmann Repetto, Anton Kern, Andrew Kreps and Kurimanzutto — pooled their resources to buy the place, which they’re also using for storage.)