PHOENIX - The East Valley Tribune in the Phoenix suburb of Mesa will close on Dec. 31, less than a year after embarking on an experiment to focus more on digital content and reduce the number of days it went to print.

Its demise, announced Monday, also comes just months after the newspaper won its first Pulitzer Prize, journalism's top honors.

Freedom Communications put the newspaper up for sale shortly after the company filed for bankruptcy protection in September. The newspaper received inquiries, but couldn't find a suitable buyer.

``They were looking for someone who would be a good partner for the Tribune, to move it forward, and that just didn't happen,'' Freedom spokesman Robert Emmers said, noting the company doesn't currently have plans to sell any of its other newspapers.

Those include two other Phoenix-area Freedom newspapers, the Daily Sun-News in Sun City and the weekly Ahwatukee Foothills News. They were part of the Tribune group that was for sale, but now will be retained by Freedom.

Irvine, Calif.-based Freedom Communications operates 33 daily and 77 weekly newspapers, including The Orange County (Calif.) Register and The Sun in Yuma, Ariz.

The company sought bankruptcy protection in September, citing a steep drop in advertising revenue and increasing competition from the Internet in recent years. The filing was part of a prepackaged plan approved by a majority of the company's lenders.

Like many newspapers, the Tribune has been hard-hit by the economic downturn and faced stiff competition for classified ads from Web sites offering free or cheaper alternatives. In addition, because it is a secondary advertising outlet for the metro Phoenix market, behind The Arizona Republic, it took the bigger hit from large retailers pulling back in the recession.

The Tribune was among the first newspapers to take a new approach to digital content by scaling back its print operations.

In January, it went from publishing a print edition all seven days to just four days a week, sending readers online for the remaining days. Just four months later, it dropped another day, leaving it with just three in print.

Nationwide, about 100 U.S. newspapers have either reduced the number of days they publish or have gone to the Web entirely, but most are smaller and dropped just one day. Others have simply shut down, including Denver's Rocky Mountain News and Gannett's Tucson (Ariz.) Citizen.

The Tribune also became a free publication delivered to driveways and newsracks in four growing communities, Mesa, Chandler, Gilbert and Queen Creek. As part of that change, the paper pulled out of Scottsdale and Tempe.

``In many ways, this paper closed when they pulled back in the market, and they had to do that because there is not enough advertising for two papers,'' McGuire said, adding that he was impressed by the Tribune's willingness to experiment with digital content.

John Morton, a veteran newspaper analyst based in Silver Spring, Md., said the newspaper's closure shows that the journalism industry has yet to find a way to transfer its business to the Internet and prosper. ``I'm not saying that every effort will fail, but it's certainly not a good sign,'' Morton said.

At its peak in 1997, the Tribune had daily circulation of 94,500. Before making its big changes last year, the paper had a combined paid and free circulation in excess of 100,000.

About 40 percent of staff was cut in December 2008, just before the switch. The newspaper said it hasn't been profitable in the past two years. About 140 employees now work at the Tribune, which will offer severance packages to employees. Some workers may be available for jobs in other parts of the company.

The Tribune won its Pulitzer in local reporting for a series of stories about how Maricopa County Sheriff Joe Arpaio's focus on immigration enforcement endangered investigations of other crimes. Paul Giblin, one of the reporters who wrote the prize-winning series, was one of a number of workers laid off last year.

Just last month, the East Valley Tribune won Arizona Newspaper of the Year honors, given by the Arizona Newspaper Association and the Arizona Associated Press Managing Editors group.