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Pennsylvania's new congressional district lines are not a game-changer

The Pennsylvania Supreme Court ...

Posted: Feb 20, 2018 2:01 PM
Updated: Feb 20, 2018 2:01 PM

The Pennsylvania Supreme Court has redrawn the state's congressional lines after declaring the current map an unconstitutional gerrymander.

The new lines are good news for Democrats. Under the old map, for example, Hillary Clinton won six of the state's 18 congressional districts. Under the new map, she would have won eight of the state's 18 congressional districts.

Still, the importance of the new map should not be oversold.

While the new map gives Democrats a better chance of taking back the House in 2018, it doesn't change the odds greatly.

You can do different types of fancy calculations, but Democrats are now probably favored in two seats that were at best toss-ups for them before: the new PA-5 and PA-6. Clinton would have won these districts by around 28 percentage points and 9 percentage points respectively under the new lines. Under the old lines, these were seats were carried by Clinton, but by just 2 percentage points or less.

A shift of two seats isn't small, though it's not exactly that large in the grand scheme. Democrats need a net gain of 24 seats to win the House in November. Two seats is less than 10% of that. You could certainly imagine instances where two seats made the difference in control of the House, though they are few and far between.

Now, the new map is beneficial to Democrats in ways beyond PA-5 and PA-6. The advantage that incumbents usually enjoy will be lessened by the new map because some Republican representatives will have many new and different constituents. Additionally, a few other seats shifted a few more points Democratic (e.g. the new PA-1), while the new PA-17 (represented currently by Keith Rothfus) shifted greatly toward the Democrats. It was won by Donald Trump by 3 points compared to 21 percentage points under the old lines.

Still, the political environment heading into 2018 will probably limit the effects of the new map. Because the national political environment is supposed to heavily favor the Democrats (for example, Democrats hold a 7-percentage-point edge in an average of recent live interview generic ballot polls), the incumbency advantage was already likely to be smaller. That's part of the reason why there were many Republican-held seats in Pennsylvania that Democrats already had a good chance of flipping under the old map.

Under the old map, the CNN House ratings had five Republican seats that were ranked lean Republican or worse for the Republicans. A sixth seat was considered likely Republican (i.e. a seat that could flip, but most likely not). Interestingly, that sixth seat, held by Rep. Lloyd Smucker, went from being won by Trump by 7 points to being won by Trump by 26 points. In other words, it's now much safer for the Republicans.

Let's take a closer look at the new map, taking into account the fact that Democrats hold about a 7-point lead on the generic congressional ballot. If you were to look only at the number of Republican seats that were won by Trump by 7 points or less or won by Clinton in 2016, the change from the old map to the new map is minimal. There were five Republican seats that met this criteria under the new map and four under the old map. Democrats will certainly welcome the one additional seat, but one seat is clearly not a game-changer.

Nationally, the number of Republican seats that are in danger of being flipped barely expanded under the new map. For instance, the number of seats won by Trump by 7 points or less or won by Clinton went from 45 to 46. The more limited playing field of Republican-held seats won by Clinton went up from 23 to 25.

It's also still the case that Democrats will have to win the national House vote by a fairly wide margin to take back the House.

Previously, I've calculated that to probably be between 5.5 and 8 percentage points. Based on some simplistic math that takes into account how many seats are now vulnerable for the Republicans and the fact that the party that has benefited from a wave has netted a pickup of approximately two-thirds of the number of vulnerable seats in the past few wave elections, Democrats may now only need to win the national popular vote by between 4.5 and 7 percentage points to take back the House. Again, that's better than it previously was for the Democrats, but it's a considerable margin and not all that different from what they needed before the Pennsylvania map was redrawn.

If Democrats want to greatly increase their chance of taking back the House, what they'll want is a change in the national political environment. Their generic ballot lead has fallen from a double-digit lead in December. If Democrats can get that lead back up to this margin, it would have a far greater impact on their hopes of taking back the House than the new map out of Pennsylvania will.

Mississippi Coronavirus Cases

Data is updated nightly.

Confirmed Cases: 67649

Reported Deaths: 1912
CountyConfirmedDeaths
Hinds5613118
DeSoto365831
Harrison252036
Madison242266
Rankin228334
Jackson227642
Jones189958
Forrest180656
Washington166341
Lee146241
Lauderdale141292
Neshoba128692
Lamar122014
Oktibbeha112239
Bolivar111334
Warren109333
Lowndes107737
Panola105913
Sunflower103925
Scott100320
Lafayette97316
Copiah95428
Pike93636
Leflore93363
Holmes89248
Grenada84721
Yazoo83112
Pontotoc8278
Lincoln81741
Monroe79655
Simpson79630
Leake78825
Wayne76721
Coahoma76013
Tate73429
Marshall6959
Marion67720
Union63616
Adams62325
Winston62016
Covington61213
George5815
Pearl River55039
Newton54211
Tallahatchie53110
Attala52225
Walthall50220
Chickasaw46219
Noxubee45711
Alcorn4285
Calhoun4189
Tishomingo4175
Prentiss41210
Claiborne40713
Smith40513
Clay39614
Hancock39014
Jasper3869
Tippah36613
Itawamba35910
Tunica3377
Clarke32726
Montgomery3265
Lawrence3238
Yalobusha31510
Humphreys29311
Quitman2691
Carroll26111
Greene25012
Perry2367
Webster23412
Kemper23314
Amite2326
Jefferson Davis2316
Wilkinson21213
Stone1995
Sharkey1975
Jefferson1967
Benton1441
Choctaw1344
Franklin1272
Issaquena261
Unassigned00

Alabama Coronavirus Cases

Confirmed Cases: 99390

Reported Deaths: 1733
CountyConfirmedDeaths
Jefferson13109243
Mobile9947207
Montgomery6835148
Madison537834
Tuscaloosa421373
Unassigned359961
Baldwin354425
Shelby328335
Marshall316736
Lee267845
Morgan239318
Etowah212131
DeKalb181913
Calhoun178414
Elmore172338
Walker152664
Houston139812
Russell13682
St. Clair133817
Limestone133313
Dallas132323
Franklin127420
Cullman122512
Colbert118113
Autauga116921
Lauderdale116719
Escambia108217
Talladega102614
Jackson9894
Tallapoosa85579
Chambers84138
Dale83424
Blount8004
Chilton7926
Butler76436
Coffee7616
Covington73520
Pike7097
Clarke6629
Barbour5755
Marion57424
Lowndes57224
Marengo55215
Hale47626
Bullock46411
Winston45311
Perry4424
Bibb4385
Wilcox42910
Monroe4214
Randolph40110
Pickens4009
Conecuh39310
Washington39112
Sumter36018
Lawrence3491
Macon33514
Crenshaw3185
Choctaw28312
Cherokee2737
Henry2633
Geneva2611
Clay2585
Greene25111
Lamar2222
Fayette2075
Cleburne1271
Coosa1012
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