These swing-state counties are key to understanding the presidential race

In the 2020 presidential election, the country was stretched ideologically and demographically. From 2012 to 2016, more than 200 counties flipped from former President Barack Obama to former President Donald Trump. In 2020, less than half that number changed hands from Trump to President Biden.

Biden won by bigger margins in cities, and Trump drove up turnout and margins in rural areas. Biden was able to win because of his strength in the suburbs and the shift of white voters with college degrees toward the Democratic Party in the Trump era — something Vice President Harris wants to try to replicate.

But there’s no guarantee that will happen again, especially as Trump has made efforts to peel off portions of traditionally Democratic groups, like young men, young Black men and working-class Latinos.

Below is a guide to the counties to keep an eye on in each of the seven swing states as returns roll in on election night and in the days afterward. These counties will help explain why the next president won. (Source for county vote data comes from the U.S. Election Atlas.)

Jump to a state: Pennsylvania | Wisconsin | Michigan | North Carolina | Georgia | Arizona | Nevada

Pennsylvania

19 electoral votes
2020 margin: D+1.18 (82,166 votes)

1. Montgomery: The most populous Philadelphia suburban county, Biden netted 40,000 more votes there in 2020 than Hillary Clinton did in 2016. Harris has to try to match that in order to win this important state. Biden saw a 120,000-vote shift statewide in his favor — 105,000 of that came from just the four suburban Philadelphia counties (Montgomery, Bucks, Delaware and Chester), which are among the highest educated, wealthiest and most populated counties in the state. Though they voted overwhelmingly for Biden in 2020, Trump can’t ignore them because he’s expected to get a significant share of votes from them, too. Harris would also like to do at least as well as Biden did in Philadelphia proper, where Democrats have seen a slight decline in their vote share since Obama was on the ballot (85% in 2012, 82% in 2016 and 81% in 2020).

2. Allegheny (and surrounding area): Biden won this county, where Pittsburgh is, in 2020. He netted nearly 40,000 more votes out of Allegheny than Clinton did four years earlier. Harris will need to try to replicate Biden’s performance because in all the counties that touch Allegheny, including Butler where Trump was shot, Trump won handily.

3. Cumberland: Trump won this central Pennsylvania county with 55%. It’s a mix of suburban and rural and sits just across the river from the state capital of Harrisburg. Biden was able to cut into Trump’s margins, netting 7,000 more votes than Clinton pulled from Trump in 2016. Biden’s 44% in the county in 2020 was the best for a Democrat since 1964. Cumberland has seen a 15% population increase since 2010, has the highest median income outside the Philadelphia collar counties and the seventh-highest college attainment of any county in the state. It’s the county with the highest level of college attainment that went Republican.

4. Lackawanna: It’s home to Scranton in the northeastern part of the state. Biden was born there and won it by more than Clinton in 2016. But it has been trending away from Democrats in the age of Trump due, in part, to its high blue-collar population.

5. Cambria: This populated, more rural county in the central western part of the state could give some clues about similar places that are crucial to Trump’s support and turnout level with his base. It’s 90% white and below the national average for college attainment and income. Like other more rural counties, it went by more for Trump in 2020 than 2016, despite him losing the state overall.

Boomerang counties*: Erie, Northampton

*Boomerang counties refer to places that went for Obama twice, Trump in 2016 and Biden in 2020.

Wisconsin

10 electoral votes
2020 margin: D+0.63 (20,682 votes)

1. Dane (Madison): This heavily Democratic county, home to Madison and the University of Wisconsin, has seen tremendous growth in the past decade. It accounted for 1 in 6 Democratic votes statewide in 2020, but 80% of the total vote-shift in Biden's favor.

2. Milwaukee: For Harris to repeat a Democratic win in the state, she’s going to have to drive up turnout in this county. It is the most populous county in the state, is 27% Black, 17% Latino and 5% Asian American. It’s also a critical place for Trump. Milwaukee County gave Trump his second highest vote total of any county outside Waukesha in the Milwaukee suburbs.

3. Waukesha: There are 72 counties in Wisconsin, and nearly 10% of all the votes cast for Trump in 2020 came from this one suburban county just west of Milwaukee. A lot is made of the fact that Trump’s margins of victory were significantly smaller in the “WOW” counties (Waukesha, Ozaukee and Washington) surrounding Milwaukee in 2020. That was largely the result of far fewer third-party votes pulling from Democrats that year. Trump got nearly the identical percentages in each of the three WOW counties in both 2016 and 2020. The four suburban counties that touch Milwaukee — the WOW counties plus Racine — accounted for 1 in 5 Trump votes statewide. Harris probably has to do at least as well as Biden in these suburbs to win the state.

4. La Crosse: Clinton got a bare majority in this western Wisconsin county, but Biden expanded the margin here. It could be a sign of how the state goes and how Harris performs with blue-collar white voters — it’s nearly 90% white — and with younger voters. The city of La Crosse within the county is home to three colleges and thousands of students.

5. Brown (Green Bay): Welcome to Packers Country. In fairness, the entire state is Packers Country, but Brown County is home to Green Bay. This county leans Republican, but Biden cut the margins here — again, mostly because of fewer people voting third party in 2020. Harris can’t afford to get blown out here or in neighboring Outagamie. It also has one of the higher Latino populations in the state.

Boomerang: Door, Sauk

Michigan

15 electoral votes
2020 margin: D+2.78 (154,181 votes)

1. Wayne (Detroit, Dearborn): Michigan shifted in Biden’s favor by more than 164,000 votes. A quarter of that was because of this urban county, home to Detroit and Dearborn. It will tell the story of whether Harris was able to turn out Black voters (its population is 38% Black) and how much the war in Gaza hurts Harris. Wayne is home to 100,000 Arab Americans, the largest population of Arab Americans anywhere in the country.

2. Oakland: This once-reliably Republican suburban Detroit county accounted for Biden’s largest vote shift in 2020. It’s one of the state’s wealthiest, most educated and most populous counties in the state. It also has significant Black and AAPI populations that Harris needs to turn out for her to match Biden’s success. The car industry has long roots here —Stellantis, formerly Chrysler, is headquartered here — but the health care industry is one of the county’s biggest employers and it has also seen a tech boom that has attracted younger and more diverse people.

3. Macomb: This Detroit suburb is slightly more conservative than its neighbor Oakland, and it gave Trump more votes than any other county in the state in both 2016 and 2020. But Biden was able to slice into Trump’s margin there. It’s the kind of place Trump needs to run up the score and where Harris needs to keep it close.

4. Washtenaw (Ann Arbor): Staying in the Detroit metro area, no other county gave Biden a wider margin of victory than this one. In fact, no Democrat, including Obama in 2008, won this county with a higher percentage of the vote. Home to the University of Michigan, it’s the most educated county in the state and could indicate Harris’ level of support with younger voters.

5. Kent (Grand Rapids): This county in the western part of the state could signal which direction Michigan goes. It was once a Republican stronghold, but its growth and the ideological shifts within the parties has moved it more Democratic. It was one of only three counties statewide to go from Trump in 2016 to Biden in 2020.

Boomerang: Saginaw. (Leelanau and Kent also flipped from Trump to Biden.)

North Carolina

16 electoral votes
2020 margin: R+1.3 (74,483 votes)

1. Wake (Raleigh): It’s the most populous county in the state and one of the fastest-growing in the country. That has meant a huge shift in its politics in favor of Democrats. In 2004, Republican George W. Bush won it with 51%. By 2008, Obama got 57% of the vote. Biden in 2020 won it with 63%. His margin of victory — 167,000 — is 25,000 more than all of the votes Bush got in the county in 2000. Biden saw a 100,000-vote shift in his favor in the state; 60% of it came from this county. Harris has to drive up the score here with young voters and the state’s most educated voters and white-collar professionals in other parts of the Research Triangle, like Durham and Orange, home to a host of big-name universities, like N.C. State, the University of North Carolina-Chapel Hill, Duke and Wake Forest.

2. Mecklenburg (Charlotte): Charlotte is one of the fastest-growing cities in the country. The county has seen a 21% population increase since 2010 and that has helped Democrats make this state more competitive. Like in Wake, Biden gained an almost 60,000-vote shift here.

3. Union: Just outside Charlotte, this is the highest-populated county that Trump won in the state in 2020. It’s one of five counties that border Mecklenburg, all won by Trump. Watch the margins here. Biden was able to cut into them, and Harris will need to do the same.

4. Robeson: What insulated Trump in North Carolina largely was his strength with white voters without college degrees. It’s the one state of the seven swing states in 2020 where he saw an increase in his vote margin with non-college white voters. But this county, one of the poorest and most diverse in the state, represents what Trump’s team has been able to do in appealing to rural, nonwhite voters. Robeson is 42% Native American, almost a quarter Black, 12% Latino, and had long voted Democratic. Yet Trump flipped it in 2016, then expanded his margin in 2020, winning with 59% of the vote there. He held one of his final rallies of the 2020 campaign in Robeson, pushing his message of the “forgotten” men and women after declaring his support for federal legislation that would recognize the Lumbee tribe.

5. Henderson: This is one of the more populous Trump-won counties affected by Hurricane Helene in western North Carolina. Trump won a majority of the votes in counties affected by Helene. Turnout there will give some idea how Trump’s vote is affected. Neighboring Buncombe County, home to Asheville, voted heavily Democratic, so Harris’ campaign will be watching turnout closely there, as well.

Boomerang: None. (Nash and New Hanover flipped from Trump to Biden. Scotland went from Biden to Trump.)

Georgia

16 electoral votes
2020 margin: D+0.23 (11,779 votes)

1. Gwinnett: This county, which was long Republican-held, represents the growing — and diverse — suburbs in the Atlanta area (and in the country) that helped Biden win the state for Democrats for the first time since 1992. It has seen a population boom in the past decade, has a higher-than-average median income than the rest of the country, and it is majority nonwhite. Biden won it with 58%, up from 50% in 2020 and 45% for the Obama-Biden ticket in 2012. Does that pace continue? The growth in the Atlanta area is the main reason Democrats have made the state more competitive. Similarly, pay attention to Cobb and Henry.

2. Hall: This is one of those populous, heavily Republican metro Atlanta counties Trump won by huge margins in 2020, but he won them by less than he did in 2016. To make up what was such a narrow margin statewide, Trump will look to drive up the score in places like this. Similarly, watch Paulding to the north and west of the city.

3. Clayton: Just south of Atlanta, this will be a good test of Harris’ ability to turn out Black voters. It’s 73% Black, 15% Latino and is the sixth-most populated county in the state.

4. Chatham (Savannah): So much attention is paid to the Atlanta metro area because of its size and growth, but watch the margins in places like Chatham, home to Savannah. It’s among the counties Biden won in 2020 by more than Clinton did in 2016. Some notable others: Muscogee (Columbus), Richmond (Augusta), Bibb (Macon), Baldwin.

5. Columbia: Just outside Augusta, this is one of those Trump-won counties, where Biden shrunk the margins. Others include: Houston (outside Macon), Effingham (outside Savannah), Glynn (Brunswick), Camden, Thomas and Lowndes.

6. Peach: This low-population county in the south central portion of the state won’t shift the state in a significant way by itself, but it will be a test of whether Harris can turn out rural Black voters to offset Trump’s strength with white, non-college voters. It’s 44% Black, went twice for Obama, but then flipped to Trump in 2016 and 2020, when Trump won it by a slightly higher margin.

Boomerang: None. And no counties flipped Trump to Biden, either.

Arizona

11 electoral votes
2020 margin: D+0.31 (10,457 votes) 

1. Maricopa (Phoenix): Biden won the state by just over 10,000 votes, with a 100,000-vote swing from 2016 — 90% of that came from Maricopa, home to Phoenix. It was the first time in decades that Democrats had won the county, and it gave Biden 61% of his votes statewide in 2020.

2. Pima (Tucson): Biden ran up the score in this traditionally Democratic county. He netted 40,000 more votes here than Clinton in 2016. Similarly, watch Coconino (Flagstaff) and Apache, where Biden ran up the score in these Democratic-leaning counties.

3. Pinal: Trump won by wider margins in Republican-leaning counties like this one than in 2016. But look to see if that trend continues here and also Yavapai, Mohave, Yuma and Cochise.

Boomerang: None. But Maricopa was the big flip here from Trump to Biden.

Nevada

6 electoral votes
2020 margin: D+2.39 (33,596 votes)

1. Clark (Las Vegas): Two-thirds of all the votes in the state come from this county, which is home to Las Vegas. It will tell us whether Trump’s appeals on the economy to working-class Latino voters resonate. It is also home to a significant share of Asian American and Black voters.

2. Washoe (Reno): It has mirrored the statewide vote percentages for both parties in every presidential election since 2004 — and went with the winner each time.

Boomerang: None. Washoe is the key swing county.