Just about every great work of 20th-century modern art at Seattle Art Museum since the 1960s—Jasper Johns's Thermometer, Helen Frankenthaler's Painting with Frame, and works by Mark Rothko, Robert Irwin, Carl Andre, Jo Baer, and more and more and more—well, they've all been provided by two people: Virginia and Bagley Wright.

Bagley died in 2011, and Virginia is now 85. She was unable to comment for this story because she was on a plane from New York. She isn't collecting any longer, and she's sold the building where she had been storing and exhibiting their collection for years, and so now, most of the remarkable collection finally lands permanently at SAM.

The Wright Exhibition Space, which was free and open to the public since 1999 and where Virginia had free rein to curate all kinds of gorgeous shows, is closing permanently October 14, according to collections manager Jan Day.

"One door closes and another opens," Day wrote in an email.

The door that's opening is that the 84 works of art that were being stored and exhibited at the Wright Space are now being officially transferred to SAM, where they will be continuously available to go on display as SAM brings them out.

They'll not all be out at once at first. They'll trickle out a few at a time, into the modern galleries, starting in spring 2015, and then more will be featured in a large abstraction exhibition being organized for summer 2016. (A large Wright collection show, of 72 works, did happen in 1999, and a thorough catalog is out there; I'm not sure whether it's out of print.)

It's not news that the Wright Collection is coming to SAM: they've always been associated with SAM, and promised to give their works along with other donors who made similar promises when the museum opened in its new facility a few years ago.

But anything can happen between a promise and its fulfillment, as many museums have discovered, to their dismay.

"To me, the big news on this story is that this is the first of these collections that were promised as gifts for our 75th anniversary that are actually being turned over to a gift," SAM director Kimerly Rorschach told me. "When all these collections come in—although I think this is the biggest—we will have such an amazing collection of postwar American art. We'll be up there with San Francisco, maybe even surpassing them."

(Jockeying statements like these are common, and I struggle to assess their truth. We don't yet know what's actually promised, or whether it will arrive, or what will happen in the interim. At the same time, the claims reflect the ambitions of the institution, so I think it's well worth reporting them.)

One of those major collections that's been promised but not yet delivered is the holding of Eastsider Barney Ebsworth, who owns significant works by artists including Joseph Stella, Edward Hopper, and David Hockney. To the Pop Departures exhibition that SAM is opening this week, Ebsworth is loaning pieces by Claes Oldenburg and Wayne Thiebaud, so his relationship with SAM seems to be doing just fine—although it's long been reported that he is also courted, and lends to, the National Gallery of Art in Washington, D.C.

Rorschach said there's no specific timeline for any other promises to become gifts; in many cases, they will be bequests.

The Wrights have previously given 144 works to SAM, but of those, 91 were Japanese textiles. This grouping of 84 is the most significant chunk ever to come in. Still, 62 works remain pledged from the Wright Collection as future gifts. Some of those, Rorschach guessed, are simply pieces Virginia Wright still loves living with.

Virginia's eye for modernism, especially abstraction, is legendary. The Wrights essentially led the way for contemporary art collecting in Seattle, taking on a role something like Joseph Schapiro's in Chicago. "They got others inspired," Rorscach said. "She would say to you now that her taste is the old masters of modern and contemporary art and she's not still buying artists out on the leading edge, but she did in her day, and it's just amazing what's been put together."

Many of the Wright works have been seen repeatedly over the years, but some will be "startling to some people, I think," Rorschach said, citing Alfred Jensen's Cheops Testament, a 25-foot-long abstraction the Wrights bought in 2007 (picture taken at the Wright Space), according to Sheila Farr's Seattle Times report.

The closing of the Wright Exhibition space is "a real loss, it really is," Rorschach said. "She could do anything she wanted there, and it gave you a sense of her eye and her intellectual commitment to it all."

How will SAM make extra room for all this new art now here, and on its way in the coming years?

Back in 2007, I explained the original plan—before the Washington Mutual crash: "By renting eight floors in the SAM building that the museum eventually would move into, the bank—in a handsome and deceptively slender-looking tower by NBBJ—would cover SAM's mortgage until the museum was ready to expand."

Put simply: SAM owns 12 floors but occupies only the first four. After WaMu crashed, Nordstrom took over the lease and moved into those 8 upper floors (so hastily vacated by WaMu). SAM will have the option, Rorschach said, to expand upward in 2031. The museum is currently 118,000 square feet. The additional 8 floors are another 240,000 square feet.

"We don't have to take them all over," Rorschach said. There will be several variables—whether SAM needs the rental income or the space more, for one. "It's a ways away," she said. For now, most of the greatest collection of modern art in Seattle history has at least found its permanent home, even if there's not quite the space to show enough of it just yet.