Technical Reference Glossary, Links		Initiative Constitutional Amendment for Automated Districting

Supreme Court | Computer Programming

1990 Census Statistics for California

Districting Seats For California:
California Assembly: 80
California Senate: 40
Board of Equalization: 4
US House of Representative: 52
(Census estimates suggest that California will gain
one or two seats in the Y2K Apportionment)

1990 Census Tracts in California
Total Tracts: 3,757
Zero Population markers and adjustments: 36
Total Populated Tracts: 3,721

Total Census Blocks: 5,858
Zero Population markers and adjustments: 187
Total Populated Blocks: 5,671

County Definitions: 58
Place Definitions: 876

Census Mapping Reference
Boundary Data Points: 154,864
Boundary Adjustment Points:
Populated Boundary Points: 149,152

Longtitude / Latitude Reference
North Extreme: 42.009655
South Extreme: 32.534100
West Extreme: -124.407951
East Extreme: -114.130432
State Centroid: 37.271878, -119.269192

See: Decennial Census
Link: US Census Bureau
Link: US Census Mapping Service

US Supreme Court Decisions
on Apportionment and Districting

Bush v. Vera, 116 S. Ct. 1941 (1996)
Shaw v. Hunt, 116 S. Ct. 1894 (1996)
Miller v. Johnson, 115 S. Ct. 2475 (1995)
Johnson v. DeGrandy, 114 S. Ct. 2647 (1994)
Growe v. Emison, 507 U.S. 25 (1993)
Shaw v. Reno, 509 U.S. 630 (1993)
Voinovich v. Quilter, 507 U.S. 146 (1993)
Franklin v. Massachusetts, 505 U.S. 788 (1992)
U.S. Dept. of Commerce v. Montana, 503 U.S. 442 (1992)
Board of Estimate v. Morris, 489 U.S. 688 (1989)
Davis v. Bandemer, 478 U.S. 109 (1986)
Thornburg v. Gingles, 478 U.S. 30 (1986)
City of Lockhart v. U.S., 460 U.S. 125 (1985)
Brown v. Thomson, 462 U.S. 835 (1983)
Karcher v. Daggett, 462 U.S. 725 (1983)
City of Mobile v. Bolden, 446 U.S. 55 (1980)
Connor v. Finch, 431 U.S. 407 (1977)
United Jewish Organizations of Williamsburgh, Inc. v. Carey, 430 U.S. 144 (1977)
Beer v. United States, 425 U.S. 130 (1976)
Chapman v. Meier, 420 U.S. 1 (1975)
Gaffney v. Cummings, 412 U.S. 735 (1973)
Mahan v. Howell, 410 U.S. 315 (1973)
Burns v. Richardson, 384 U.S. 73 (1966)
Reynolds v. Sims, 377 U.S. 533 (1964)
Wesberry v. Sanders, 376 U.S. 1 (1964)

United States Constitution Article I, Section 2
Fourteenth Amendment (Equal Protection Clause)

Voting Rights Act of 1965, Section 2, coded as amended at 42 U.S.C. 1973
Voting Rights Act of 1965, Section 5, coded as amended at 42 U.S. C. 1973c

Computer Programming

The automated method of creating electoral districts can be manually, or run on a personal computer in a few hours. Although the Initiative doesn't actually contain programming code, the instructions in the Election Code section can be translated into any computer language. One of the more common and English-like languages is dBase, which is available for personal computers at a modest price. The popular Foxbase(c) implementation for Windows is available from many suppliers. A sample set of Foxbase programs and data files can be downloaded from this site.
Jump: Download Code and Data

There are only a few steps required to implement the districting program. Sample program (PRG) and Data Base Files are all named with the prefix CEnsus and use letters to identify their purpose:

• New boundary data points for Tracts and Blocks will be available early in the year 2000. A simple program (Ce_TrAtt.Prg) calculates the center point of each TRact from longtitude and latitude COOrdinates (Ce_TrCoo.Dbf) and transfers them into a Tract ATTribute file (Ce_TrAtt.Dbf) for later reference.
• Population counts for each tract and block will be available late in the year 2000. The Census Bureau makes the numbers available in several formats, including DBF. The block counts, along with the centroid, and tract codes are easily consolidated (Ce_Tract.Prg) into a combined Tract file (Ce_Tract.Dbf).
• The consolidated data (Ce_Tract.Dbf) is indexed by multiplying the longtitude and latitude of all the tract centroids. The indexing creates the Northwest to Southeast sequence for the districting seed process. The first unassigned tract in sequence is used to start each district centroid, which is a simple average of the extremities of the boundaries.
• The final process is performed by the Districting program (Ce_Distr.Prg), which calculates totals, averages, and steps through the Tract file (Ce_Tract.Dbf) to first pick a seed tract, then find the closest adjacent tracts, and accumulate their population until the gross variance (1%) for the district is met. With each additional tract, a new centroid for the district is calculated until the process generates a valid district.
  The centroid, accumulated population and district information is stored in the District file (Ce_Distr.Dbf). When the first district type, State Assembly seats, is completed, the program nests them into sets for State Senate and Board of Equalization. The scan and accumulate process is repeated for US House of Representative seats.
• The final list of tracts comprising each district may then be printed or mapped to show the completed districting process.

Among the steps, the only complex process is calculating the proximity of adjacent tracts to the district centroid. The formula for calculating mileage distances between any two points on earth is common and well established. Mathematically, it uses uses the radius of the earth and the longtitude and latitude of two points to calculate the distance:
MILES = (ACOS(COS(lat1)*COS(lon1)*COS(lat2)*COS(lon2)+COS(lat1)*SIN(lon1)
*COS(lat2)*SIN(lon2)+SIN(lat1)*SIN(lat2)))/ 360* 2*PI* 3963

The automated process is graphically demonstrated in an animated sequence on this site.
Jump: Districting Animation

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