The Pew report adds that some of these problems seem to be manifesting themselves on the content side. When data from 2012 is compared with stations studied in 2005 and earlier, the amount of time devoted to edited story packages has decreased, and average story lengths have shortened -- signs that there is less in-depth journalism being produced.

        Traffic, weather and sports -- the kind of information now available on demand in a variety of digital platforms -- seems to be making up an ever-larger component of the local news menu, according to the stations studied in 2005 and 2012. Coverage of politics and government, meanwhile, was down by more than 50 percent.

        Part of the decrease in edited packages and story lengths may reflect the fact that with local stations continuing to add news programming, particularly in the morning, editorial resources are stretched thinner.

        In 2011, the last year for which data exists, stations aired a record 5 hours and 30 minutes of local news on weekdays in 2011, or 12 minutes more per week than the previous year.