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Midwest Mapping Project: Illinois

Midwest Mapping Project: Illinois. Michael McDonald George Mason University. Supported by The Joyce Foundation. Talk Overview. Understanding the importance of census geography Lessons learned The mapping project Lessons learned. What is a Census Block?. Block 001. Block 002.

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Midwest Mapping Project: Illinois

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  1. Midwest Mapping Project:Illinois Michael McDonald George Mason University Supported by The Joyce Foundation

  2. Talk Overview • Understanding the importance of census geography • Lessons learned • The mapping project • Lessons learned

  3. What is a Census Block? Block 001 Block 002

  4. What is a Census Block? Springfield, Illinois

  5. What is a Census Place? Springfield, Illinois

  6. How to Draw Grid Districts Illinois Counties & Census Places

  7. How to Draw Grid Districts Example Congressional Grid Plan

  8. How to Draw Grid Districts Example Congressional Grid Plan

  9. How to Draw Grid Districts Example Lower House Grid Plan

  10. Important Lessons • Equal population districts must be of unequal geographic size; urban districts must be smaller than rural districts • Nicely-shaped districts are difficult to draw using census blocks; and may conflict with respecting existing political boundaries • Different approaches may be necessary to draw congressional and state legislative districts

  11. The Mapping Project • Three mappers drew one plan for Congress and both state legislative chambers for each of these four types of plans: • Grid Districts • Compact Districts • Respect County Boundaries • Respect Census Place (City) Boundaries • These test plans are almost certainly not the absolute best that may be achieved • 2000 Census and Election Data used to evaluate plans • Legislative districts are not “nested”

  12. The Mapping Project The full report is available at: http://elections.gmu.edu/Redistricting.html

  13. Illinois’ Current Plans “Two-party vote” is the 2000 Presidential vote for the two major party candidates: Super = greater than 80% Strong = 80% to 55% Lean = 55% to 50% “Bias” is the number of Democratic majority seats minus the statewide two-party vote. A negative value indicates a pro-Republican plan. Majority Black or Hispanic districts have greater than 50% minority Voting Age Population.

  14. Congressional Test Plans “Two-party vote” is the 2000 Presidential vote for the two major party candidates: Super = greater than 80% Strong = 80% to 55% Lean = 55% to 50% “Bias” is the number of Democratic majority seats minus the statewide two-party vote. A negative value indicates a pro-Republican plan. • Majority Black or Hispanic districts have greater than 50% minority Voting Age Population. Averages for three test plans presented.

  15. State Senate Test Plans “Two-party vote” is the 2000 Presidential vote for the two major party candidates: Super = greater than 80% Strong = 80% to 55% Lean = 55% to 50% “Bias” is the number of Democratic majority seats minus the statewide two-party vote. A negative value indicates a pro-Republican plan. • Majority Black or Hispanic districts have greater than 50% minority Voting Age Population. • Averages for three test plans presented.

  16. State House Test Plans “Two-party vote” is the 2000 Presidential vote for the two major party candidates: Super = greater than 80% Strong = 80% to 55% Lean = 55% to 50% “Bias” is the number of Democratic majority seats minus the statewide two-party vote. A negative value indicates a pro-Republican plan. • Majority Black or Hispanic districts have greater than 50% minority Voting Age Population. • Averages for three test plans presented.

  17. Important Lessons • The Republicans tend to be advantaged in every test plan. • The test plans tend to have more competitive districts. • No test plan has as many minority-majority districts as the current plans. Geographic criteria may be in conflict with the Voting Rights Act.

  18. Why Geographic Criteria Tend to Benefit Republicans Illinois Partisan Composition 2000 Two-Party Vote, Blue = Democrat, Red = Republican

  19. Why Geographic Criteria Benefit Republicans • Democrats tend to be least disadvantaged in grid and compact plans that do not follow existing political boundaries • Democrats systematically do worst in plans that respect county boundaries • Concentrate Democrats in Cook County • Split Downstate communities like West and East Peoria, which straddle the Peoria and Tazewell county line • Respecting census places (cities) tends to be a middle ground by permitting districts to cross the Cook County line and by promoting the combining of Downstate cities

  20. Important Lessons • Redistricting criteria can have predictable partisan and racial effects • If goals like partisan fairness or competition are desired, they should be codified into law, just as we do with minority representation goals described in the Voting Rights Act

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