We asked: What do you think are the biggest stories of the past decade? Here's what NBC News and MSNBC readers and viewers shared.

Numbers indicate the number of submissions per story.

Donald Trump

Donald J. Trump's victory in the 2016 presidential election was nothing short of a political earthquake — and the aftershocks continue to rock the lives of Americans. The real estate developer and former reality television star has virtually monopolized headlines for nearly every day of his presidency, thrilling his supporters and alarming his critics with hard-right policy moves, incendiary rhetoric and a freewheeling Twitter feed.

Trump, who is gearing up for re-election in 2020, has already reshaped the landscape with a massive tax cut, sweeping changes to immigration rules, and the consolidation of the conservative majority on the Supreme Court. No matter the outcome of November’s election, Trump has unequivocally redefined the presidency for many years to come.

Climate Change

Washington may be divided on the correct response to global warming, but huge swaths of people across the world, from progressive political leaders to average citizens and activists, are convinced that climate change represents the gravest and most pressing threat to the planet. What’s more, many scientists expect that the issue — caused by the burning of coal, oil and gas — could get far worse by the end of the century.

Trump, for his part, has announced his intention to pull out of the landmark 2015 Paris Agreement. But people in states and cities across the United States and many parts of the world remain committed to curbing greenhouse gas emissions and continue to push for more comprehensive action. Swedish teenager Greta Thunberg, meanwhile, emerged this year as a global conscience for environmental activism. (She also made the cut for the biggest story of the decade as chosen by NBC News readers and viewers).

Russian Interference

America's intelligence agencies agree: Russian President Vladimir Putin's government meddled in the 2016 presidential election, aiming to sow social discord and boost Trump's anti-establishment candidacy. The interference campaign, with tactics ranging from fake news and digital disinformation to the hacking of the Democratic National Committee, have been heavily dissected and hotly debated throughout much of Trump's time in the Oval Office.

Russian election interference, characterized by some as an unprecedented subversion of American democracy, was also one of the focal points of former special counsel Robert Mueller's investigation into possible ties between Trump campaign associates and Putin's government. Mueller ultimately found no proof that Trump criminally colluded with Russia, but senior officials continue to sound the alarm about Russia's plans for 2020.

Impeachment

The fourth-biggest story of the decade is still being written: Earlier this month, Trump became only the third president in U.S. history to be impeached after the Democratic-led House of Representatives charged him with committing high crimes and misdemeanors. The process will eventually move to a trial in the GOP-controlled Senate.

Democrats accuse Trump of violating his oath of office in pressuring Ukraine to announce investigations into former Vice President Joe Biden and his son Hunter while withholding some $400 million in aid, as well as obstructing Congress by refusing to release any documents related to his actions. Trump, who has angrily pushed back against the House’s proceedings, now becomes the first president to run for re-election after being impeached.

Barack Obama

Barack Obama’s re-election in 2012 cemented his barrier-breaking place in history and symbolized the dramatic cultural changes of the decade. Obama’s second term in the White House was often hindered by fierce GOP opposition in Congress, although he notched a series of progressive victories, including signing the Paris Agreement, reaching a nuclear deal with Iran and negotiating rapprochement with Cuba.

But simmering domestic unrest, including the rise of the Black Lives Matter movement, and mounting anger in many parts of the world over the unequal recovery from the global financial crisis frequently tested the limits of Obama’s political appeal. The resurgence of anti-establishment populism in his final months in office — Brexit, Trump’s election — also threatened to erode much of his legacy.

And yet for many Americans, Obama remains an inspirational figure — admired for his soaring rhetoric, steady leadership and history-making ascent to the White House.