It’s the end of an era: Copley Press announced today that it’s exploring a sale of the San Diego Union-Tribune. The U-T’s president and CEO said the newspaper is caught up in a “perfect storm” affecting all media organizations.

“Part of it is secular – that is, brought about by forces that are fundamentally changing our business model and making it impossible for us to continue doing business as usual. The other part is cyclical, brought on by the collapse in the real estate market that is affecting the entire country, but is slamming Sun Belt cities especially hard.”

It’s a big day for San Diego, and for people who resent the old order that Copley represented and the virtual stranglehold that the U-T had on the city, it’s a happy one. Copley and the U-T were the only game in town for many, many years, intimately tied in to the city’s and the GOP power structure in a way that few newspapers ever were.

I’ve written about some of this before: James Copley allowed his news service to provide cover for CIA operatives. Editors like Herb Klein and Jerry Warren moved back and forth from journalism into the Nixon White House.

The newspaper was a kingmaker in this law-and-order town, and it was part of what kept San Diego the lone conservative bastion on the Left Coast. It nurtured people like Bill Kolender, the city’s former police chief and current sheriff. He was hired on as an assistant to the publisher while he pondered his next political move. Lately, the U-T has tangled with progressive City Attorney Mike “We’re Marching On” Aguirre.

Copley was once a chain of newspapers in the Midwest and Southern California. All were sold in the hopes, I suppose, of saving the Union-Tribune, the crown jewel. Even in its weakened state, the newspaper remains a powerhouse. Its estimated revenues in 2006 of $387 million were more than all the local TV stations in town combined.  But the company can’t limp along any more.

In the end, it was the mortgage and real crisis that pushed Copley to this. Which is ironic, because the Union-Tribune, like the old L.A. Times under Colonel Otis and the OC Register, were relentless promoters of growth. Think big.  Build it and they will come.

But what goes up must come down.  San Diego just can’t expand any more because nobody wants to live in Temecula and pay $4 gas for the privilege of driving hours back and forth to work every day. Something’s gotta give.

Gene Bell, the Union-Tribune president and CEO, says newspapers aren’t dying. Maybe, maybe not. But the once mighty newspaper will never be the same.