Biden outpaced Obama’s totals in 2008 and when he was reelected in 2012 because 1) the country has gotten more populous, 2) there was a lot of enthusiasm for voting this year and 3) much of that enthusiasm from Democrats was targeted not at Biden, but at Trump.
In 2008, the population of the United States was about 299 million. Four years later, it was up to about 309 million. Now, it’s over 330 million. The number of adult citizens — that is, those eligible to vote — has also increased, up an estimated 25 million since 2008.
Biden earned about 80 million votes as of counting. (This will increase given outstanding ballots in New York and California.) That’s 11 million more than Obama in 2008. Assume that two-thirds of the newly added adult citizens voted this year and that’s an addition of 17 million more people to the voter pool even ignoring issues of enthusiasm. Split that in half and Biden would just need to find 2.5 million more votes somewhere.
We can look at the boost for Biden in another way. Biden’s total this year is about 15 percent higher than what Obama got in 2008 and 21 percent higher of his total in 2012. Trump’s total this year is 23 percent higher than what former senator John McCain got in 2008 — and an equivalent 21 percent higher than what Mitt Romney got eight years ago.