A two-part documentary on PBS titled America’s Great Divide: From Obama to Trump looks for an answer to the question of how the U.S. got so hyperpolarized.

How did the U.S. go from electing its first African-American president to electing a president in immediate succession who has been touted as a totem for racism and xenophobia? The growing political divide in the U.S. is evident in these last two presidencies and is the subject of a new documentary series on PBS.

Aptly titled America’s Great Divide: From Obama to Trump, the two-part four-hour documentary will air as part of the PBS “Frontline” series. Directed by veteran “Frontline” filmmaker Michael Kirk, who has covered everything from the 2008 financial crisis to the Iraq War, the new documentary draws from new interviews with key political and cultural figures, as well as featuring unparalleled archives of broadcast reporting from both presidential administrations.

Part one of the new documentary starts chronologically with Barack Obama at his final State of the Union address, in which he cited the increasing mistrust between both political parties was one the few regrets of his presidency. Indeed, the documentary explores how Obama’s original message of hope for the U.S. would be undermined by increasing racial, cultural and political divisions — setting the stage for the rise of Donald Trump.

Part Two examines how Trump’s campaign exploited the country’s divisions, how his presidency has fired up both sides of the divide, and what this polarization could mean for America’s future.

Theories exploring the cause of the divide include the great recession of 2008 and its cataclysmic repercussions for politics. With the recession occurring shortly before Obama was first elected president, it would inevitably color the public’s perception of him and his party in office.

Another speculation is that 2008 vice presidential candidate Sarah Palin enhanced the polarization of both parties with her unorthodox persona and approach to politics: charges of her distorting facts would pave the way for claims of fake news that plague Trump’s presidency.

Overall, the documentary casts a wide net and touches on several key events in the nation during this time that may have contributed to the current cultural war: the Trayvon Martin killing, Brett Kavanaugh’s Supreme Court confirmation hearings, birtherism, and the White Nationalist rally in Charlottesville. It attempts to show both sides of the aisle as well, with audio from liberal late-night TV hosts and conservative talk radio broadcasts.

America’s Great Divide: From Obama to Trump premiered on PBS, Monday, Jan. 13 and Tuesday, Jan. 14 at 9 p.m. E.S.T. It will also be available in full on the PBS website and on the PBS Video App beginning Mon., Jan. 13 at 6 p.m. E.S.T.