William Frey looks at presidential voting by geography and concludes that suburban voters gave Biden his victory:

In the 2016 election, rural and nonmetropolitan America gave Donald Trump enough of a margin to beat Hillary Clinton in seven key states. Ahead of the 2020 election, Republicans worried that Trump would lose his rural edge, in light of reduced support there in the 2018 midterm elections. But this was not the case. Instead, Trump’s loss to Joe Biden was due mostly to voters in large metropolitan suburbs, especially in important battleground states…

However, large suburban areas in 2020 registered a net Democratic advantage for the first time since Barack Obama’s victory in 2008. This is significant because more voters reside there than in the other three categories. In terms of aggregate votes in these large suburban counties, there was a shift from a 1.2 million vote advantage for Trump in 2016 to (at last count) a 613,000 vote advantage for Biden—a nearly 2 million vote flip. In addition, Biden benefitted from more modest Republican margins in small metropolitan areas. These advantages for the President-elect were even greater in key battleground states…

The three northern battleground states of Michigan, Pennsylvania, and Wisconsin—which flipped to Trump in 2016—again entered the Democratic fold in 2020. Here, even more than in the national analysis, the 2016 to 2020 suburban shifts to either greater Democratic or smaller Republican support were instrumental in Biden’s victory…

Suburban voting patterns also made a difference in the Sun Belt, especially in large southern states where suburbanization has been rampant. The focus here is on two such states: Georgia, where Biden is ahead and a recount has been announced; and Texas, which Trump won, but where urban and suburban voting patterns closed the longtime Republican-Democratic gap.

This is the most detailed analysis I have seen thus far. The predictions were right: the 2020 presidential election depended on the suburbs!

It also brings several other features of American and political life into relief:

1. Joe Biden was nominated in part because of his electability. In the long run, his electability in one particular kind of place was particularly important: suburbs. Trump, to some degree, knew this but his approach was more combative and did not have the appeal he hoped.
2. While political analysis suggests middle suburbs are battleground areas, I wonder if this signals that these suburbs are also in the middle of all sorts of other trends including demographic changes, cultural tastes, and suburban inequality. To build on earlier posts, perhaps finding middle America right now involves going to a Walmart in a middle suburb or an emergency room in a middle suburb.
3. Many people have discussed the electoral college in recent years. Here is a crazier proposal based on more recent trends: instead of the electoral college by states, how about an electoral college by cities, suburbs, and rural areas? With concerns on either side that cities or rural areas are controlling political outcomes, could there be some way to weight the results such that all three geographies could influence the outcome? Grouping votes by states obliterates any distinctions between places.