Across the United States, more than 30 daily newspapers are for sale, and buyers are scarce. From Los Angeles to New York, leading newspapers have slashed newsrooms with buyout offers, and when those failed to reach budget-cutting goals, with layoffs. The newspaper industry has been caught in a tailspin for three years, a trend variously blamed on plummeting ad revenues, declining readership, growing competition from the Internet and a deepening national recession. On Thursday, Colorado’s oldest newspaper joined the growing list of dailies on the market. E.W. Scripps Co., owner of the 149-year-old Rocky Mountain News, offered to sell it after reporting an $11 million loss through the first nine months of this year. ‘It’s a terrible time to put the Rocky Mountain News up for sale, clearly,’ said John Morton, a veteran newspaper-industry analyst in Maryland. ‘Whatever price they might attract probably will be quite low. I think it’s going to be very difficult to find a buyer.’ The main culprit in the newspaper business decline: shrinking classified-ad sections. Newspapers depend on advertising for about four-fifths of their revenue, and at big-city dailies, the classifieds used to bring in half of that money. […]