Do newspaper endorsements matter?

Not everyone thinks so. In a 2008 study by the Pew Research Center , 69 percent of respondents said a newspaper endorsement had "no effect" on their vote.

But a research paper published in the National Bureau of Economic Research that year found an exception: When they were unexpected. For example, if a conservative editorial board endorsed a Democrat or a liberal editorial board endorsed a Republican.

It's still early for newspaper endorsements for Republican Donald Trump, Democrat Hillary Clinton and Libertarian Gary Johnson, but already there have been a few.

See the list below for some of the unexpected endorsements so far.

Democratic Nominee for President of the United States former Secretary of State Hillary Clinton speaks to and meets voters during a rally at Frontline Outreach and Youth Center in Orlando, Florida on Wednesday September 21, 2016. The Washington Post—The Washington Post/Getty Images Cincinnati Enquirer: Clinton Publication: The Cincinnati Enquirer State: Ohio is a battleground state Endorsement History: Republican. The last Democratic presidential nominee that the newspaper endorsed was Woodrow Wilson in 1916 . 2016 Endorsement: Clinton Quote: "Trump is a clear and present danger to our country. He has no history of governance that should engender any confidence from voters. Trump has no foreign policy experience, and the fact that he doesn't recognize it – instead insisting that, 'I know more about ISIS than the generals do' – is even more troubling."

For a day of Pennsylvania campaigning, Democratic Nominee for President of the United States former Secretary of State Hillary Clinton speaks to reporters during a press conference in Harrisburg, Pennsylvania on Tuesday October 4, 2016. The Washington Post—The Washington Post/Getty Images Columbus Dispatch: Clinton Publication: The Columbus Dispatch State: Ohio is a battleground state Endorsement History: Republican. The last time the newspaper endorsed a Democratic presidential candidate was Woodrow Wilson in 1916. 2016 Endorsement: Clinton Quote: "For us, the choice between Hillary Clinton and Donald Trump is not pleasant, but it isn’t difficult. Republican candidate Donald Trump is unfit to be president of the United States. Democrat Hillary Clinton, despite her flaws, is well-equipped for the job."

Hillary Clinton meets voters during a rally in Raleigh, North Carolina on Sept. 27, 2016. The Washington Post—The Washington Post/Getty Images Arizona Republic: Clinton Publication : The Arizona Republic State : Arizona is not currently a battleground state Endorsement History : Republican. The newspaper has never before endorsed a Democratic presidential nominee over a Republican since its publication began in 1890. 2016 Endorsement : Clinton Quote : “This year is different. The 2016 Republican candidate is not conservative and he is not qualified. That’s why, for the first time in our history, The Arizona Republic will support a Democrat for president.”

Democratic Nominee for President of the United States former Secretary of State Hillary Clinton speaks to journalists after meeting national security experts for a National Security Working Session at the New York Historical Society Library in Manhattan, New York on Friday September 9, 2016. The Washington Post—The Washington Post/Getty Images Dallas Morning News: Clinton Publication: The Dallas Morning News State: Texas is safe Trump territory Endorsement History: Republican. The last time the Morning News didn't endorse the Republican nominee was 1964, when it was neutral in the contest between Lyndon Johnson and Barry Goldwater. 2016 Endorsement: Clinton Quote: "We've been critical of Clinton's handling of certain issues in the past. But unlike Donald Trump, Hillary Clinton has experience in actual governance, a record of service and a willingness to delve into real policy. Resume vs. resume, judgment vs. judgment, this election is no contest."

Democratic Nominee for President of the United States former Secretary of State Hillary Clinton speaks to journalists after meeting national security experts for a National Security Working Session at the New York Historical Society Library in Manhattan, New York on Friday September 9, 2016. The Washington Post—The Washington Post/Getty Images Houston Chronicle: Clinton Publication: The Houston Chronicle State: Texas is safe Trump territory Endorsement History: Republican. The newspaper typically backs the Republican nominee with two exceptions: Lyndon Johnson in 1964 and Barack Obama in 2008. 2016 Endorsement: Clinton Quote: "Any one of Trump's less-than-sterling qualities—his erratic temperament, his dodgy business practices, his racism, his Putin-like strongman inclinations and faux-populist demagoguery, his contempt for the rule of law, his ignorance—is enough to be disqualifying. His convention-speech comment, 'I alone can fix it,' should make every American shudder. He is, we believe, a danger to the Republic."

For a day of Pennsylvania campaigning, Democratic Nominee for President of the United States former Secretary of State Hillary Clinton, along with her daughter Chelsea Clinton, participate in a roundtable about families at Haverford Community Recreation and Environmental Center in Haverford, Pa., on Oct. 4, 2016. The Washington Post/Getty Images The Atlantic: Clinton Publication: The Atlantic State: A national magazine, it is based in Washington, D.C. Endorsement History: Not much. The magazine has endorsed only twice before: Republican Abraham Lincoln in 1860 and Democrat Lyndon Johnson in 1964. 2016 Endorsement: Clinton Quote: "We are impressed by many of the qualities of the Democratic Party’s nominee for president, even as we are exasperated by others, but we are mainly concerned with the Republican Party’s nominee, Donald J. Trump, who might be the most ostentatiously unqualified major-party candidate in the 227-year history of the American presidency."

Gary Johnson, 2016 Libertarian presidential nominee, listens to questions from audience members during a campaign event at Purdue University in West Lafayette, Indiana, U.S., on Tuesday, Sept. 13, 2016. Bloomberg—Bloomberg via Getty Images Richmond Times-Dispatch: Johnson Publication: The Richmond Times-Dispatch State: Virginia is a battleground state Endorsement History: Republican. The Times-Dispatch has endorsed the Republican nominee for president since 1980. 2016 Endorsement: Johnson Quote: "Neither Donald Trump nor Hillary Clinton meets the fundamental moral and professional standards we have every right to expect of an American president. Fortunately, there is a reasonable—and formidable—alternative."

Gary Johnson, 2016 Libertarian presidential nominee, speaks during a campaign event at Purdue University in West Lafayette, Indiana, U.S., on Tuesday, Sept. 13, 2016. Bloomberg—Bloomberg via Getty Images Winston-Salem Journal: Johnson Publication: The Winston-Salem Journal State: North Carolina is a battleground state Endorsement History: Mixed. The newspaper endorsed George W. Bush in 2000, neither candidate in 2004, John McCain in 2008 and Barack Obama in 2012. 2016 Endorsement: Johnson Quote: "We’ve surprised even ourselves with this endorsement, our first for a Libertarian for president. But the timing has never been better for this particular Libertarian, Gary Johnson of New Mexico. He is everything the presidential candidates for the two major parties are not, thank God."

Libertarian presidential candidate Gary Johnson talks to a crowd of supporters at a rally on August 6, 2015 in Salt Lake City, Utah. George Frey—Getty Images New Hampshire Union Leader: Johnson Publication: The New Hampshire Union Leader State: New Hampshire is a battleground state Endorsement History: Republican. The newspaper has endorsed the Republican presidential nominee for over 100 years. 2016 Endorsement: Johnson Quote: "Voters leaning toward Trump are understandably fed up with the status quo, of which Clinton is a prime example. But they kid themselves if they think Trump isn’t pretty much a part of that status quo as well, or that he is in any way qualified to competently lead this nation."