UPDATE 1-Gannett shutters Tucson Citizen's print edition

* Says dramatic changes and weak economy forced its hand

NEW YORK, May 15 (Reuters) - USA Today publisher Gannett Co (GCI.N) said on Friday it is closing down the print edition of the Arizona newspaper Tucson Citizen but will keep operating its website at www.tucsoncitizen.com.

Gannett said the last print edition of Tucson Citizen will be published on Saturday, May 16 after "dramatic changes" in the newspaper industry combined with the difficult economy in Tucson region forced its hand.

"It no longer viable to produce two daily printed newspapers in Tucson," said Bob Dickey, president of the U.S. Community Publishing unit of Gannett.

Lee Enterprises publishes the Arizona Daily Star newspaper. It also formed a joint operating agreement with Gannett to publish the Citizen. Such agreements are forged in certain instances to allow multiple newspapers in one city. That agreement ends on Saturday.

Lee plans to publish a Tucson Citizen weekly editorial in the Daily Star as part of a partnership with Gannett.

Tucson Citizen was founded in 1859 and Gannett said it is the oldest continuously published newspaper in Arizona.

U.S. newspapers have struggled with rapidly decline advertising and shrinking print circulations as readers have moved online.

This year has proven to be pivotal for the U.S. newspaper business. Some big-city dailies, including E.W. Scripps Co's (SSP.N) Rocky Mountain News, have closed. Hearst Corp's Seattle Post-Intelligencer has stopped its print edition and has an online edition that is far smaller than the printed newspaper was.

Others, like the New York Times Co (NYT.N)-owned Boston Globe and Hearst's San Francisco Chronicle, face the threat of shutdown. (Reporting by Yinka Adegoke; Editing by Derek Caney)