A head to head comparison of the North Carolina 2020 Primary gives us an idea of the break down of the voters.
Donald Trump received 750,600 (38%) votes to beat Joe Biden, who received 572,271 (29%) votes and Bernie Sanders, who received 322,645 (16%) votes.
In the Primary, Trump won 72 counties in the 3-way match up. Biden trailed behind Trump winning 26 counties with Sanders winning 2 counties in North Carolina Primary.
Bernie Sanders vs Joe Biden
Joe Biden vs Donald Trump
Donald Trump vs Joe Biden
In the head to head match ups, Sanders (64%) beat Biden (36%). Trump (70%) beat Sanders (30%). Also, Trump (57%) beat Biden (43%).
These 10 counties play an important role in these Primary elections. If a candidate, can get a sizable majority in the larger counties (Wake, Mecklenburg and Guilford), it becomes very difficult to win majorities in the smaller counties without voter outreach and increased voter participation in them
Wake and Mecklenburg, two of the larger counties voted in favor of Biden, giving him over 65k vote advantage over Trump and over 61k vote advantage over Sanders in just those two counties. However, Trump's steady win in many of the less dense counties contributed to the vote advantage that helped him gain an upper hand in the State of North Carolina.