This is the study in question. Yes, American media have always been biased. It is the Partisan Press all over again. You do not need a study to see people in the news media are nose-tweakers.
It is all about inciting audiences, not informing them. In Canada, it is all about placating jittery masses so they don't panic or no matter how lousy they have it in life, still feel superior to someone else.
But the study is very bad science. What is defined as news, for instance? We don't know and that greatly weakens this "study."
And it misses the boat in one key area: local news is dead. We wouldn't have so many local newspapers -- and online versions folding if there was an actual interest in it.
People may want to tell the researcher they have interest in local news, but give them a quiz on the basics, and they will fail, meaning that "interest" does not translate to actual usage.
There were better ways to conduct a study, but Pew ignored it, for whatever reason...