As the landscape of competitive House races takes shape, I’ve been interested in the geography of the Blue Wave. Which states will be most important for taking back the House this November?

It’s hard to answer this question precisely, so I decided to focus on a more straightforward one: which states are projected to have the largest change in the proportional makeup of their Congressional delegations in the midterm elections?

It turns out my home state of New Jersey is poised for the biggest change in its Congressional composition, while other big moves are possible in Obama-Trump states (Iowa, Pennsylvania) as well as rapidly Dem-trending states (Arizona, Virginia). Read on for the full breakdown.

Methodology

I’m making use of the fantastic work of the folks maintaining the Prognosticator Tracking spreadsheets. Using historical performance as a baseline, they provide probabilities of each seat flipping based on its rating from the three big election handicappers: Cook Political Report, Sabato’s Crystal Ball, and Inside Elections with Nathan Gonzales.

I use these probabilities to compute an expected value for the number of Democratic-held Congressional seats in each state after November’s elections. These are expected values, not projections, so fractional seats are possible. I then compare these expected values against the current makeup of the Congressional delegation.

Note that the current ratings indicate Democrats are poised to gain about 20 seats — just shy of the 23 seats needed to flip Congress. Ratings have been trending toward Dems over the past two years and will likely continue to do so, so these estimates are not final. But they start to give us an understanding of where dense opportunities exist for Democrats.

Results

Results for each state are summarized below.

State # Seats Current

Democratic

Proportion Expected

Democratic

Proportion Expected

Change New Jersey 12 58% 77% 19% Iowa 4 25% 43% 18% Montana 1 0% 15% 15% Pennsylvania 18 33% 48% 14% Maine 2 50% 64% 14% Virginia 11 36% 50% 14% Arizona 9 44% 54% 9% Kansas 4 0% 7% 7% Colorado 7 43% 50% 7% Nebraska 3 0% 7% 7% Michigan 14 36% 42% 6% California 53 74% 79% 5% Florida 27 41% 46% 5% Washington 10 60% 65% 5% Illinois 18 61% 66% 5% Kentucky 6 17% 21% 5% New York 27 67% 71% 4% Utah 4 0% 4% 4% Ohio 16 25% 29% 4% North Carolina 13 23% 26% 3% Texas 36 31% 33% 3% Arizona 4 0% 3% 3% Wisconsin 8 38% 40% 2% Minnesota 8 63% 65% 2% Georgia 14 29% 30% 2% West Virginia 3 0% 2% 2% New Mexico 3 67% 68% 1% Oklahoma 5 0% 1% 1% Missouri 8 25% 25% 0% Indiana 9 22% 23% 0% Arkansas 1 0% 0% 0% Alabama 7 14% 14% 0% Connecticut 5 100% 100% 0% Delaware 1 100% 100% 0% Hawaii 2 100% 100% 0% Idaho 2 0% 0% 0% Louisiana 6 17% 17% 0% Massachusetts 9 100% 100% 0% Maryland 8 88% 88% 0% Mississippi 4 25% 25% 0% North Dakota 1 0% 0% 0% Oregon 5 80% 80% 0% Rhode Island 2 100% 100% 0% South Carolina 7 14% 14% 0% South Dakota 1 0% 0% 0% Tennessee 9 22% 22% 0% Vermont 1 100% 100% 0% Wyoming 1 0% 0% 0% Nevada 4 75% 72% -3% New Hampshire 2 100% 94% -6%

Highlights

The Blue Garden State

New Jersey tops the list — and for good reason: of its five Republican-held CDs, Trump lost one (NJ-7) and won three by seven or fewer points (NJ-2, NJ-3, NJ-11). The incumbent Congressman is retiring in both NJ-2 and NJ-11, and the former seat has essentially been ceded to the Democrats after it was revealed that the Republican nominee had made racist comments.

Meanwhile, Democrats have attracted strong recruits in Mikie Sherill for the 11th and Tom Malinowski for the 7th, putting these seats in contention for the first time in years. And even in the less heralded NJ-3 race, Obama staffer Andy Kim is polling competitively with incumbent Tom MacArthur. Democrats currently hold seven of the state’s 12 seats, but could conceivably pick up as many as four more in November.

The Big Eastern Movers

Fellow populous eastern states Pennsylvania and Virginia are also near the top of the list, but for different reasons. Pennsylvania was redistricted under an order from the State Supreme Court, unwinding the extraordinary gerrymandering that had yielded a 5R-13D delegation from a state with a nearly even partisan divide. The new map gives Democrats a number of terrific opportunities. Pennsylvania would, in fact, have come in above NJ had Conor Lamb not won his special election in PA-18 in March, handing Democrats one more seat ahead of the midterms.

Virginia’s districts are intact, but the state’s Dems are hoping to harness the energy that powered them to a near-takeover of the State House of Delegates last fall. All eyes are on ousting moderate Republican Barbara Comstock in VA-10, who has held on through challenging elections but is facing her toughest race yet against Dem State Senator Jennifer Wexton. VA Dems have recruited strong women candidates for several other competitive races, including former CIA Officer Abigail Spanberger in VA-7 and former Navy Commander Elaine Luria in VA-2.

Smaller State Opportunities

A few smaller states, such as Iowa, Montana, and Maine, also rank high by virtue of having one or two competitive districts.

Iowa is the most interesting case, as three of its four Congressional districts swung from Obama in 2012 to Trump in 2016. One of those districts is D-held and is considered safe, while the other two — IA-01 and IA-03 — are R-held and hotly contested. Just as in Virginia, the competitive seats are being contested by female Democrats, including yet another badass Abigail (state legislator Abby Finkenauer) as well as businesswoman Cindy Axne.

In Montana, incumbent carpetbagging rich guy/bodyslammer in chief Greg Gianforte could be vulnerable in this otherwise very red state. Democrat Kathleen Williams is behind in cash but could conceivably pull off an upset. In Maine, it all comes down to whether Dems’ strong nominee, Jared Golden, can unseat Bruce Poliquin in ME-02.

Big Blue States Have Pockets of Competition

Notably, the three biggest solid blue states — California, New York, and Illinois — do not rank in the top ten. Opportunities exist in these states, but they’re not particularly concentrated.

Part of this has to do with Dems’ existing strength. Team Blue already comprises at least 60% of each state’s delegation, so there is limited room to grow. Many of the opportunities in November have emerged due to the realignment of college-educated white voters (putting districts like CA-45 and IL-6 in play) or due to weak or junior Republican incumbents (IL-12, NY-19, CA-10).

These states are certainly important, and Dems must focus on maximizing their contributions to a potential Blue Wave. But the delegations of big, solidly Democratic states won’t be as profoundly altered in November as those of some smaller and swingier states.

Non-Competitive States and Republican Opportunities

Only about one in four Congressional seats are considered competitive. So it’s not surprising that 20 states have no expected change in their Congressional representation, including some relatively large states like Massachusetts and Tennessee. Some races in these states may become more competitive before Election Day. But this is a disturbing demonstration of the effects of gerrymandering, ideological sorting, and partisan polarization: many states simply don’t have competitive districts.

The only states with a (very slight) expected shift toward Republicans are New Hampshire and Nevada. Retirements are the driving factor: Democrats Carol Shea-Porter (NH-1), Ruben Kihuen (NV-4) and Jacky Rosen (NV-3) all occupy swing seats and are not seeking reelection (Rosen to run for Senate). Since these seats are now somewhat competitive, Dems’ expected representation in the delegation has fallen slightly. But Dems have recruited strong candidates for all three seats, and I expect them to stay in Democratic hands.