Mail voting in 2020 US primaries became more common as COVID-19 spread | Pew Research Center
2016 Democratic Party presidential primaries - Wikipedia
Democrats 2016: The Primary Map Still Favors Clinton – Sabato's Crystal Ball
Maryland Presidential Primaries 2016: latest Democratic polls Apr 2016 | Statista
Political polarization and the 2016 congressional primaries
File:U.S. states (and territories) by election methods, 2016 (Democratic Party).svg - Wikimedia Commons
Trump's big advantage: open primaries.
2016 Republican Party presidential primaries - Wikipedia
2016 Presidential Election Calendar- WSJ.com
The Modern History of the Republican Presidential Primary, 1976-2012 – Sabato's Crystal Ball
2024 Republican primaries may be a rerun of 2016 | The Hill
2016 Delegate Count and Primary Results - The New York Times
Lessons from the 2022 Primaries–what do they tell us about America's political parties and the midterm elections?
Storylines to Watch in Tuesday's 2016 Presidential Primaries and Republican Caucuses - ABC News
US presidential election 2016: the state of the Republican race as the year begins | Republicans | The Guardian
The Republican debate: meet the 2016 candidates | US elections 2016 | The Guardian
Turnout in 2016 primaries so far rivals 2008 record | Pew Research Center
2016 United States presidential election - Wikipedia
Campaign 2016: Understanding the presidential election - The Washington Post
South flexes its political muscle in 2016 primaries | Facing South
Why Immigration May Decide the 2016 Election - New American Economy
Here's Why The 2016 Republican Presidential Primary Could Make History - ABC News
United States Presidential Election of 2016 | History & Facts | Britannica
Some Democrats voting in GOP primaries to block Trump picks | AP News
