Our project to calculate the 2020 presidential results for all 435 congressional districts nationwide takes the turnpike through New Jersey, which is home to a number of competitive House seats. You can find our detailed calculations here, a large-size map of the results here, and our permanent, bookmarkable link for all 435 districts here.
Joe Biden’s 57-41 victory in the Garden State was only slightly larger than Hillary Clinton’s 55-41 performance in 2016, an improvement due in part to the decline in third-party voting, but there were plenty of big changes below the surface. Biden captured nine of the state’s 12 House seats, which was two more than Clinton took last time, while Donald Trump held on to the remaining three seats. All of the Biden districts are controlled by Democrats, while Republican representatives prevailed in two of the trio of Trump seats.
We’ll start with a look at the one Democratic-held Trump seat, Rep. Andy Kim’s 3rd District, which was also the state’s closest district in the 2020 presidential race by far. Barack Obama had carried this South Jersey constituency, which is located in the Philadelphia suburbs and central Jersey Shore, 52-47 days after Hurricane Sandy devastated the area in 2012, but it swung hard to the right four years later and backed Trump 51-45. This time, the 3rd settled between those poles and supported Trump 49.4-49.2, a margin of about 800 votes.
Local Republicans in past years have run well ahead of the top of the ticket here, but the opposite happened in 2020. Kim won a second term by beating Republican David Richter 52-45, a result that was considerably wider than his 50-49 victory against Republican Rep. Tom MacArthur in 2018.
GOP outside groups opted not to spend to boost Richter, a decision that may have had to do with the sheer cost of running for office in what may be the most expensive place in the nation to advertise: About 57% of the 3rd is in the pricey Philadelphia media market, while the balance is in the very expensive New York City market. To reach all voters on television, it's necessary to blanket both—an extremely costly proposition. Kim's mammoth fundraising made that heavy lift possible, but Richter's weak finances put such an undertaking out of reach.
Republicans, however, had more success in the 2nd District just to the south. This coastal seat swung from 54-45 Obama to 51-46 Trump in 2016, and it favored Trump again last year, though by a smaller 51-48 margin. National Democrats worked hard last year to deny a second term to Republican Rep. Jeff Van Drew, who had switched from the Democrats to the GOP in late 2019 after opposing Trump’s first impeachment. But Congress' most infamous turncoat ran ahead of the man he’d pledged his “undying support” to and defeated Democrat Amy Kennedy 52-46.
Trump’s best seat by far, unsurprisingly, was once again the 4th District to the north in the Monmouth County area, though he did drop from 56-41 in 2016 to 55-44 last year. This constituency is held by 21-term Rep. Chris Smith, who was the only Republican in the state’s delegation from January 2019 until Van Drew switched parties nearly a year later.
We’ll now move up north and hit the two Trump/Biden seats, both of which began the decade as conservative turf. The 5th District in northern Bergen County and more distant exurban areas had lurched slightly to the left, going from 51-48 Romney to 49-48 Trump in 2016, but Trump’s toxicity in the suburbs helped propel Biden to a 52-47 win. The seat is held by Democratic Rep. Josh Gottheimer, a moderate who unseated arch-conservative Scott Garrett in 2016 and secured his third term 53-46 last year.
The swing to the left was even more pronounced in the neighboring 11th District in the Morris County area. This ancestrally red region had gone from 52-47 Romney to 49-48 Trump in 2016, but Biden took it 53-46 this time. Democratic Rep. Mikie Sherrill flipped this seat in 2018 by winning the race to succeed longtime Rep. Rodney Frelinghuysen and successfully defended it 53-47 in 2020.
Trump also bombed in the 7th District just to the south, though the GOP showed signs of life downballot. This seat, which includes Hunterdon County and New York City's western exurbs, had already swung hard from 52-46 Romney to 49-48 Clinton, and Biden’s margin ballooned to 54-44. Democratic Rep. Tom Malinowski, though, won his second term by a considerably smaller 51-49 margin in a very expensive race against state Senate Minority Leader Tom Kean Jr., who is the son and namesake of well-regarded former Gov. Tom Kean Sr.
While Trump’s margin took a nose dive in all of New Jersey’s competitive seats, though, he did make gains in a trio of safely blue constituencies in the northern part of the state. Rep. Albio Sires’ 8th District in Jersey City dropped from 76-21 Clinton to 73-26 Biden, which fits with the pattern we’ve seen in other seats with large Latino electorates. Rep. Donald Payne’s heavily Black 10th District in Newark likewise ticked down from 85-13 Clinton 83-16 Biden. Finally, Rep. Bill Pascrell’s diverse 9th District, which is home to Paterson and some of New York City's closer-in suburbs, shifted from 64-33 Clinton to 62-37 Biden.
Democrats have full control of the New Jersey state government, but that doesn’t guarantee that they’ll get a favorable congressional map for the coming decade. That’s because a 1995 state constitutional amendment created a bipartisan redistricting commission consisting of six Democrats, six Republicans, and a tiebreaking member. Last time, the crucial 13th member favored GOP-drawn boundaries over those proposed by Democrats, though Republican mapmakers didn’t anticipate the leftward swing that would later unfold in the state’s northern suburbs.