Hearst is threatening to close the Chronicle, leaving San Francisco with the dubious distinction of being the biggest US city without a daily (and, one presumes, without a book section… one of the last two remaining).

The historic newspaper company says the Chronicle’s 1,500 staff must agree to deep cuts and at least scores of redundancies within the next few weeks if they want to save the paper.

The crisis in the US newspaper industry has accelerated in the past few weeks, as proprietors respond to a collapse in advertising revenue that has been compounding the longer-term problem of declining readership. Dozens of local titles are under threat of closure and two regional newspaper groups went bankrupt last weekend.

The San Francisco Chronicle would be by far the biggest casualty to date. It is the 12th most read paper in the US, serving the country’s 14th largest city by population. Gavin Newsom, the San Francisco mayor, warned of the consequences of its closure. “The Chronicle plays an important role in our civic life and we don’t want to see this treasured institution close its doors,” he said.