It's not clear the reusables have done that in any significant way. Indirect measures suggest that plastic bag production has remained relatively steady.
What is clear is that reusables have taken off as a cultural phenomenon, social statement, and even art form.
And, some worry, not all to the good.
"People are accumulating too many of these, so we're back to the original problem," said Vince Cobb, a Chicago businessman who reinvented himself as a reusable-bag expert and salesman at www.reuseit.com.
"The whole thing is to consume less," he said.
So he was appalled when the Chicago Bears gave away 40,000 reusable bags at a 2009 game. Many were thrown away by halftime.
Perhaps it was inevitable that a culture hooked on shopping would find itself obsessed with bags.
More companies are giving bags away as promotional items - eco versions of the coffee mug. Last week, Target gave away a million.
For many companies, "getting their name out in what is perceived as a socially and environmentally responsible way is a good thing to do," said Leonard Lodish, professor of marketing and vice dean of social impact at the Wharton School of the University of Pennsylvania.
They come in every form imaginable: Stretchable, foldable, stuffable, made from recycled plastic bottles and juice cartons. A Philadelphia woman even crochets throwaway plastic bags into new reusables.
Not every reusable bag is environmentally equal. A nonwoven polypropylene bag, for example, would have to be used just 11 times to make up for the negative effects of a plastic bag used one time, according to a British Environment Agency study that compared bags. A cotton bag, however, would have to be used 131 times.
Reusables sell for as little as 99 cents. Or you can pay $20 for the Center City District's "banner bags," made from banners that once hung from city light posts to advertise the flower show or Ben Franklin's Tercentenary.
The fabric is washed by Philacor, a vocational training program of the Philadelphia prison system. The bags are stitched by Baker Industries, a nonprofit work-rehab program for people with disabilities, in recovery, on parole, or homeless.
Another social bag effort: A U.S. company, what'Surbag, is using bags to raise awareness - and money - for victims of the Japan earthquake and tsunami.
Reusable bags have taken on such cachet that a just-released book celebrates them as an art form. The Tote Bag, by the British designer Jitesh Patel, even has a jacket that doubles as a reusable bag.
Among dozens of "striking, inventive, and subversive examples," Patel selected one from Philadelphia.
The bag is printed with a funky lumberjack image by Rob Marshbank and Julia Cagninelli, designers with Red Tettemer + Partners. The ad agency sent out about 200 in place of a holiday card in 2008.
Cobb, the Chicago bag man, said that was around the time that plastic bags began showing up on mainstream lists of "things you can do to save the planet."
They're still here.
The American Chemistry Council - the closest thing to an umbrella group for plastic bag makers - tracks only the film they are made of, not the number of bags, said Keith Christman, senior director of packaging for the trade group. He said film production has mostly remained steady. He blamed a recent dip on the economic downturn.
What has risen, he said, is plastic bag recycling. Between 2008 and 2009, the volume increased 3 percent. Collected in groceries and other big box stores, the bags are turned into everything from lumber to other bags.
Still, only a small minority of bags is returned for recycling.
A few supermarket chains have stopped using plastic bags, and some cities and states have proposed fees or restrictions. Many failed or were challenged in the courts by the plastic industry.
Bills in Trenton, Harrisburg, and Philadelphia have gone nowhere.
Volunteers who worked on the city's recent cleanup "commented constantly on how many bags they had to clean up," said Councilman Jim Kenney, who cosponsored 2009 legislation and said this week that he may do so again.
San Francisco was among the first to ban the bags. The District of Columbia taxes them.
In January 2010, a five-cent fee on all single-use bags - paper and plastic - provided by stores went into effect. The measure was intended to fund projects benefiting the Anacostia River, where 27 percent of the trash items were plastic bags.
The number of plastic bags used by stores is believed to have dropped significantly, although exact data were not available.
The river improved, too. At last year's spring cleanup, less than four months after the bag fee began, volunteers collected two-thirds fewer discarded bags, said Brent Bolin, director of advocacy for the Anacostia Watershed Society.
Something else also happened. As a way to blunt the effect of the tax, stores gave away reusable bags by the thousands.
"At this point, people are starting to say, 'I have more than enough reusable bags,' " Bolin said.
A local soup kitchen has started collecting them and redistributing them to the poor.
Contact staff writer Sandy Bauers at 215-854-5147 or firstname.lastname@example.org.
Visit her blog at http://go.philly.com/greenspace.