The Endless Show.

Call it "calendar creep" or simply "slow shows," but in Europe and America, art-museum exhibitions seem to be running longer and longer these days. The giant Aztec show at the Royal Academy in London, for example, will endure almost as long as that ancient civilization itself; it closes on April 11 after opening way back in November. In Dallas, a survey of modern design called "Boomerangs and Baby Boomers" debuted in August and won't pack up until March 18. New York's financially constricted Guggenheim Museum just pressed the zapper on its video anthology "Moving Pictures" after a run of almost seven months. Scotland's National Galleries won't disassemble its big exhibition of contemporary art, "Warhol to Koons," until it rivals that transition in length.

What gives? Fifteen years ago, "exhibitions used to run for about six weeks," says Lars Nittve, director of the Moderna Museet in Stockholm. "Now the 'standard' is around 10 to 12 weeks... large museums run the exhibitions for longer than that." According to Nittve, "The thinking is that it doesn't make sense to take down an exhibition if it still has pulling power." That box-office draw, according to many museum people, is the result of bigger, splashier shows and a growing audience. Today more folks would just as soon spend an afternoon at a museum as at the Cineplex, and more international cultural tourists are wandering the streets with museum guidebooks in hand.

But given the ongoing economic slump, budget-trimming must have something to do with the trend, too. After all, the total cost of installing, advertising and uninstalling two or three special exhibitions a year is a lot less than doing the same for a half-dozen shows--not to mention that expenses, especially shipping and insurance, have risen drastically during the past few years. Museums are cutting back on booking traveling shows and instead deriving more exhibitions from ...