Ever wonder why your avowed-conservative brother and fervently-liberal aunt can't even seem to agree on the facts?

It's because "when it comes to getting news about politics and government, liberals and conservatives inhabit different worlds," according to a Pew Research Center study published on Tuesday.

Conservatives say they trust Fox News and not much else. Liberals say they trust many news outlets, but not Fox.

Among other things, the study underscores Fox's unique position in the media marketplace, thanks to what it calls the "strong allegiance" that conservatives have to Fox.

Overall, among Americans of all political persuasions, CNN is the most-trusted major news outlet, according to Pew's data. 54% of survey respondents said they trusted CNN (the operator of this website), 20% said they distrusted it and 21% said neither. ABC News and NBC News followed closely behind, trusted by 50% of respondents.

44% of the respondents said they trusted Fox News, while 37% said they distrusted it -- only 12% said neither.

Pew found that partisans on both sides are not totally isolated from opposing sources. "Nearly half (47%) of across-the-board conservatives -- and 59% of across-the-board liberals -- say they at least sometimes disagree with one of their closest political discussion partners," the researchers noted.

These disagreements often take place on Facebook (FB), which is also a top source of political news, according to the study.

But local TV news outranks Facebook as the most-frequently-named source. Forty-nine percent of respondents said they received news about politics and government from local TV in the past week; 48% named Facebook; 44% named CNN; 39% named Fox News; and 37% named NBC News.

For perspective's sake, 14% said YouTube had been a source of politics and government news in the past week, and 9% named Twitter (TWTR).

Pew's findings came from an online panel of 2,901 Americans. (The firm says the study is "representative of the 89% of Americans who have access to the internet," not the whole population.)

Pew sized up the ideological leanings of each person who responded, using a 10-question survey that determines how consistently liberal or conservative the person is.

Among consistent conservatives, 88% said they trusted Fox News, 62% said they trusted Sean Hannity's radio show, 58% said they trusted Rush Limbaugh's show, and 51% said they trusted Glenn Beck's. Those were the only sources that were said to be trusted by a majority of consistent-conservative respondents. (And Pew said that each radio show had "a much narrower audience reach overall than Fox News.")

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Not surprisingly, 81% of consistent liberals said they distrusted Fox.

That same group, consistent liberals, gave NPR high marks -- with 72% saying they trust the public radio organization -- along with PBS (71%), the BBC (69%), The New York Times (62%), and NBC News (56%).

CNN, ABC News, MSNBC, and CBS News were also deemed trustworthy by more than 50% of consistent liberals.

But none of these news outlets are as dominant among liberals as Fox News is among conservatives. Take NPR, for instance: "even among those with mostly liberal views, just 23% got news from NPR in the previous week," Pew found.

What about the political middle? The results landed closer to the liberal side than the conservative side. CNN was No. 1 among Americans with mixed political views, earning the trust of 61%; the news divisions of ABC, NBC and CBS also surpassed 50%.

Some other noteworthy findings: