Books are unpacked and shelves stocked in April 2008 as McIntyre & Moore Booksellers moves to Porter Square. The store recently closed its upstairs discount annex. (Photo: Sushiesque)

Window shopping is all you can do at The McIntyre & Moore Booksellers Annex in Porter Square. The space closed quietly at the end of June, taking another 6,000 used volumes off the streets of Cambridge — a historically book-loving city that is already losing 100,000 titles from the closing of Rodney’s in Central Square.

The windows at the 1971 Massachusetts Ave. annex still reveal a few books and tables, and store co-founder and co-owner Dan Moore said Tuesday that the space wasn’t taken from him and Mike McIntyre by a longer-term lease. They simply hadn’t been selling many books there and hadn’t really been trying very hard.

“We were kind of working at cross-purposes with ourselves,” Moore said, since the pair hadn’t even been restocking.

Since the downstairs space that remains stocks about 45,000 volumes, the co-owners were able to approach the closing upstairs casually. In a way, the decision almost came down to “we didn’t want to pay for air conditioning in the hot months.”

“One day we just decided, okay, we’re not opening today,” he said.

The academically oriented used bookstore opened in Harvard Square in 1983, staying for 15 years, then moved to Somerville’s Davis Square for a decade. It moved back to Cambridge in April 2008, losing about half its space by taking over what was once the Bookcellar Café, another seller of used books, and later Unicorn Books & Spiritual Resource Center. The space had been lacking a permanent tenant for about two years.

The annex — in the same building, but diagonally to the basement space and not connected inside by stairs — was used for selling books at an extreme discount (the store website still advertises closing prices of $1 for hardcovers, 50 cents for trade paperbacks and 25 cents for pocket paperbacks), and toward the end of its time the owners were setting some of the stock outside to be taken for free. Annex books were “pretty picked over toward the end,” down to a third of normal stock, Moore said. What remains will probably be donated instead of added to what’s downstairs.

Rodney’s, the two-story bookstore at 698 Massachusetts Ave., is meanwhile down by about half its stock, according to workers there Tuesday, although it may be hard to tell the massive, ongoing 50 percent-off sale has had that much of an effect. “There’s a whole basement and warehouse to empty,” manager Jay Phillips said.

Rodney’s is still likely to be around through the end of the year. Like the McIntyre & Moore annex, there’s no date by which owner Shaw Taylor has to be out.

There’s also the possibility of Rodney’s moving if the right place can be found, worker Silas Lohrenz said. But the Central Square superstore will be a thing of the past, with most of the blame going to the economy.

Moore also sees the economy and the Internet as hurting bricks-and-mortar bookstores, where people can come in and browse, running the risk of buying more than they should — or would in a controlled, specific online search.

“It’s not only Cambridge, it’s everywhere,” Moore said. “But you’d think Cambridge would be a place that wants to sustain a bookstore.”

McIntyre & Moore Booksellers has also cut back its hours slightly, to noon to 6 p.m. Sundays, 10 a.m. to 8 p.m. Fridays and Saturdays and 10 a.m. to 6 p.m. the rest of the week.