The Primaries
With 17 hopefuls originally vying for the Republican nomination, Trump was quick to criticize and even mock the rest of the crowded Republican field, which included Texas Senator Ted Cruz, Florida Senator Marco Rubio, New Jersey Governor Chris Christie, businesswoman Carlie Fiorina, former Florida Governor Jeb Bush and Ohio Governor John Kasich.
After securing the nomination, Trump chose Mike Pence, then governor of Indiana, as his running mate for vice president.
Clinton faced her toughest competition from Vermont Senator Bernie Sanders, and, after winning enough delegates to clinch the nomination, named Tim Kaine, U.S. Senator for the state of Virginia, as her vice presidential running mate.
Third-party candidates on the ballot included Libertarian Gary Johnson and the Green Party’s Jill Stein, who won 3.28 and 1.07 percent of the popular vote, respectively.
Historical Firsts
In an election unlike any other, 2016 included a number of firsts. For her part, Clinton became the first woman to win the presidential nomination of a major party. Trump, meanwhile, became the first president in more than 60 years with no experience serving in Congress or as a governor (the only others were Dwight Eisenhower and Herbert Hoover). At the age of 70, Trump also became the oldest president in U.S. history (Ronald Reagan was 69 when he was sworn in).
The Clinton and Trump Campaigns
The top two voting issues for Americans, according to Pew Research Center, were the economy and terrorism, followed by foreign policy, health care, gun policy and immigration. During his campaign, Trump called for building a wall at the Mexican border, draining “the swamp” (meaning ending corruption in Washington, D.C.) and opposing free trade deals. Clinton’s campaign centered on health care, rights for women, minorities and LGBT and fair taxes.
But in a battle of slogans—"I'm With Her" vs. "Make America Great Again”—both campaigns were fraught with scandals and negative attacks.
Trump opponents were fueled by reports of sexual misconduct, including a leaked "Access Hollywood" recording of him bragging about groping women. Opponents also focused on Trump’s controversial comments and Tweets on immigrants, race and more, his attacks on the news media and violent protesters who lobbied for his election.
Clinton opponents, meanwhile, rallied around chants of "Lock her up," citing an ongoing FBI investigation into possible improper use of her personal email server during her time as secretary of state. The FBI concluded in July 2016 that no charges should be made in the case, but on October 28, then-FBI Director James Comey informed Congress the FBI was investigating more Clinton emails. On November 6, two days before the election, Comey reported to Congress that the additional emails did not change the agency’s prior report.
Going into election night, Clinton led in nearly all final polls. According to The New York Times and based on exit polls, Trump's win was attributed to his ability to not only consolidate the support of white voters (especially those without college degrees), but with minority and lower-income groups, as well.
Russian Interference
In January 2017, the Office of the Director of National Intelligence released a report concluding that the Russians interfered with the election to "undermine public faith in the U.S. democratic process, denigrate Secretary Clinton, and harm her electability and potential presidency.”
After Trump fired Comey for “this Russia thing,” former FBI director Robert Mueller was appointed as special counsel to investigate possible collusion between Russia and Trump’s campaign. After a 2-year investigation, Mueller submitted his findings to the Justice Department in March 2019. His team found no evidence of collusion between the Trump campaign and Russia, but concluded Russian interference occurred "in sweeping and systematic fashion." Thirty-four individuals and three companies were indicted in the investigation, several of whom were Trump associates or campaign officials.
Sources
"Presidential Election Results: Donald J. Trump Wins," August 9, 2017, The New York Times
"How Trump Won the Election According to Exit Polls," November 8, 2016, The New York Times
"US election 2016: Six Reasons It Will Make History," July 29, 2016, BBC
"Top Voting Issues in 2016 Election," July 7, 2016, The Pew Charitable Trust
"Election Results 2016," CNN
“Intelligence Report on US Hacking,” June, 1, 2017, The New York Times
“Timeline of Mueller Probe of Trump Campaign and Russia,” April 10, 2018, Reuters
"The Mueller Report, annotated," July 23, 2019, The Washington Post.