New polls show Joe Biden is winning suburbanites by a historic margin

(CNN) The new ABC News/Washington Post poll is the latest to show former Vice President Joe Biden on a roll.

He leads President Donald Trump 55% to 40% among registered voters. (It's a slightly tighter 54% to 44% among likely voters). The poll comes on top of other surveys last week from Fox News NBC News/Wall Street Journal and Quinnipiac University giving Biden anywhere from an 8 to 15 point advantage.

Biden's advantage in the polls is most evident in the suburbs, where he is earning a historic amount of support for a Democrat.

Biden is up by a 52% to 43% margin among suburban voters in the ABC News/Washington Post poll.

Other polls in the last month show Biden in as good or even better position among suburban voters. The latest Fox News poll has Biden with 49% to 38% lead. Quinnipiac University poll puts Biden ahead by a 56% to 34% margin with suburbanites. The NPR/PBS NewsHour/Marist Poll has Biden beating Trump 60% to 35% among suburban voters.

Our early June CNN poll had Biden with a 14-point lead in the suburbs.

In the average of all the polls, Biden's ahead by more than 15 points with suburban voters. This is a historic margin, if it holds.

The fact that Biden is doing so well in the suburbs shouldn't be a surprise. The suburbs are a bellwether vote of sorts in our current political environment. That is, the suburban vote mirrors the national vote closer than the urban or rural vote.

Biden's lead in the suburbs is reflective of him doing significantly better than Hillary Clinton. Four years ago at this time, Trump was beating Clinton by a 45% to 35% margin in the ABC/Washington Post poll among suburban voters.

In other words, we're looking at nearly a 20-point improvement for Biden versus where Clinton was at this point in the 2016 campaign.

A look across the final polls and post-election polls from four years ago shows anything from a small Clinton advantage (e.g. 5 points in the final Fox News poll ) to a small Trump advantage (e.g. 4 points in the exit poll ).

If you were to go back over time, the exit poll data reveals that no Democrat has won the suburban vote by more than 5 points since at least 1972 , when the first exit poll was taken in a presidential election.

Winning Democratic candidates do tend to carry the suburbs, though none by as much as any of the polls currently have Biden ahead in them. Back in 2008 (the best year for Democrats this century), Obama won in the suburbs by 2 points in the exit polls. The final ABC News/Washington Post poll had him winning in the suburbs by 5 points.

Lyndon Johnson in 1964 was maybe the only Democrat in the last 70 years who probably won by double-digits in the suburbs. He won overall by 23 points that year. Although no exit poll data is available from that year, the American National Election Studies shows he did about 10 points worse in the suburbs than he did nationally

The clear difference between the 1964 and 2020 elections is that Biden, at this point, is running ahead of his national numbers in the suburbs. Biden's lead overall in the polls with a suburban crosstab averages out to be about 13 points.

You can see this dynamic play out in a state like Pennsylvania. In the latest Monmouth University poll , Biden leads 53% to 40% overall among registered voters. He scores a 54% to 35% margin in the swing areas from the Philadelphia suburbs to northeast Pennsylvania. Clinton won those counties by a mere point four years ago, as she lost the state by 1 point.

Indeed, the suburbs have been a problem for Trump and the Republicans during the Trump presidency. It was the suburbs that delivered the Democrats their House majority in 2018. They picked up the vast majority of their net 40-seat gain in the suburbs.

Looking at the polling right now, it would seem the suburbs may be doing Republicans in again. Unless Trump turns it around in the suburbs, he could be heading towards being a one-term president.

This story has been updated with additional polling data.