PA senate districts: no or fewer splits

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These proposed changes: (1) reduce the number of counties divided into 2 or more districts by 2. (Centre, Lackawanna) (2) reduce the number of districts 2 counties are split into. (Chester, Montgomery) (3) reduce the number of counties Philadelphia shares districts with. The proposed change is in 3 parts, that can be implemented independently, population wise. When all 3 parts are implemented, the proposed district partisan balance closely matches preliminary district partisan balance. The proposed changes do not split any municipalities. In several places more "string like" districts were make more "ball like". All numbers are found using, using the link provided by the redistricting committee. The changes associated proposed change part 2 and part 3 are extensive. See the map at for details A summary of the end result of the proposed change is: Two fewer counties are split; Centre and Lackawanna counties are both in a single proposed district. Pike county is no longer split; that split is now in Monroe county, between the urban and suburban Stroudsburg area. Luzerne county is split between 3 districts instead of 4. Berks county is split between 4 districts instead of 3. Chester county is split between 2 districts instead of 3. Montgomery county is split between 4 districts instead of 6. In Philadelphia county, 2 districts are split with another county instead of 3. population bias (D) vs (R) vs (O): 51.16% vs 46.37% vs 2.47% preliminary (D) vs (R) vs (competitive): 22 vs 20 vs 8 (4D , 4R) proposed (D) vs (R) vs (competitive): 21 vs 21 vs 8 (5D , 3R) Proposed change part 1 - Centre county no longer split between two districts Affected districts: 25, 35, 41 Directly affected counties: Centre, Elk, Jefferson (a) Center county is no longer split between two districts, and is entirely in district 25 (b) Elk county is moved to district 35 from district 25 (c) Jefferson county (25 part) is moved to district 35 from district 25 (d) In Jefferson county, the boundary between districts 41 and proposed 35 is moved to better balance the populations between proposed districts 41 and 35 (e) partisanship associated with districts 25,35 has changed, both districts lean (R) in both mappings: preliminary 59.22,60.04 to proposed 53.59,64.90. Proposed change part 2 - Lackawanna county no longer split between two districts Affected districts:11, 14, 16, 18, 20, 22, 27, 29, 40, 48 Directly affected counties: Berks, Carbon, Lackawanna, Lehigh, Luzerne, Monroe, Northampton, Pike, Schuylkill, Susquehanna, Wayne, Wyoming See map for changes. They are too extensive to enumerate. Proposed change part 3 - Minimize SE county boundary crossings and county splitting Affected districts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 17, 19, 24, 26, 44 Directly affected counties: Bucks, Chester, Delaware, Montgomery, Philadelphia See map for changes. They are too extensive to enumerate. Other comments: (1) The minimizing of county splits provides some resistance against voting shenanigans at the county level. Any such county-wide shenanigans would only affect the districts containing that county. This situation also acts as a deterrent to creating such shenanigans in the first place. (2) The south-east district boundaries are somewhat sensitive to partisan bias. When changing them, be sure to verify the partisan bias has not changed. In particular: (a) West Chester was moved from proposed district 19 to proposed district 44, with several municipalities in the north of those two districts moved in the opposite direction. (b) Schwenksville was moved from proposed district 24 to proposed district 17, with Douglass and New Hanover moved in the opposite direction. Those two changes made late in the drawing of the proposed map helped to maintain the partisan bias present in that region in the preliminary map. (3) Philadelphia ward boundaries did not make it into The precinct names were used to verify wards boundaries were not crossed. Using, it is not possible to visualize ward boundaries, unlike city lines. (4) Municipal boundaries sometimes result in odd shaped districts. For the areas affected by these changes at least, there was no need to divide any municipality along its precinct boundaries, assuming Philadelphia wards are treated as municipalities. (5) The relative position of proposed districts 4 and 12 are flipped relative to their preliminary counterparts. The drawing of the district boundaries was a manual, iterative process; those two districts moved around a lot during modifications. (6) The proposed district containing Bethlehem (18) is spread across 3 counties (Northampton, Lehigh, and Berks) to keep the proposed district containing Allentown (16) confined to 1 county (Lehigh). Allentown and Bethlehem's combined population is too high to group into a single district without shenanigans. (7) Chadds Ford in Delaware county is joined with Birmingham in Chester county since Birmingham is not contiguous. Grouping Chadds Ford with Birmingham results in a contiguous proposed district 44, even though the boundary between Chester and Delaware counties would not otherwise need to be split. The Birminham situation makes Chester county not contiguous too, which makes such a split unavoidable. In the proposed districts 9 and 44, Chadds Ford can be moved between the two districts and not appreciably affect either population balance or partisan balance. (8) The 10% allowed population deviation (+/- 5% from average) permits sufficient freedom in population to avoid the need to split municipality boundaries. The rule disallowing unnecessary municipality splits is an effective deterrent to shenanigans.

Quantitative Analysis

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