Data Resources/Attachments/19/Redistricting - Data House.pdf

Bob West - Policy Chief
Florida House of Representatives
Redistricting Committee
400 HOB The Capitol
402 South Monroe Street
Tallahassee, FL 32399
Office 850-922-9457
Follow MyDistrictBuilder on Facebook
Follow MyDistrictBuilder on Twitter
Follow MyDistrictBuilder on YouTube
Follow MyDistrictBuilder on SlideShare
Redistricting Archives at
Questions or Comments about MyDistrictBuilder, email:

Mail to: Bob West
Florida House of Representatives
400 House Office Building
402 South Monroe Street
Tallahassee, Florida 32399-1300


Welcome to the Florida House of Representatives MyDistrictBuilder codeplex site. This site is a project of the House Redistricting Committee. The purpose of the website is to help everyone in Florida have a part in the drawing of new Congressional, State Senate and State House legislative districts to be used in the 2012 elections and afterwards. The Florida House of Representatives wants your input into this important process. This site will give you the data and programs the Florida House will use and let you draw district for just your area or the whole state and then send them to the legislature for their consideration.

To start MyDistrictBuilder go to: You will be asked to load the Microsoft’s Silverlight program. Silverlight is a program much like Flash or the PDF plug-in that you may already be using with your browser. You will also be asked for some disk space on your computer. This disk space is for what Silverlight calls ‘isolated storage’. MyDistrictBuilder uses this disk space to secure the definition of the districts that you are drawing on your local computer. This way only someone that has access to your computer will be able to see your district plan unless you send them a copy of your plan.

Quick Start

  • If you want to explore the program and discover what it can do, click on the “File” tab and then “Open.” You will be able to choose from Congressional, Senate and House past (1992) or present (2002) districts.
  • Full screen viewing and menu options can be found by clicking on the “View” tab.
  • As you zoom in and out, use “Layers” on the left to explore counties, cities, and other units of census geography.
  • If you want to start building districts right away, click the “File” tab and then “New” to start a new House, Senate, Congressional or Custom plan.
The default “District Count” corresponds to the maximum number of districts allowed.
  • Select the “Build” tab.
*Select the district you wish to work with from the scrolling “District” menu.
*Select the layer you wish to “Build With” from the drop down menu.
*To assign geography to a district, change the “Explore” selection to either “Click” or “Lasso.”
*Use the “Layers” on the far left to view the layers you are building with.
*If you want to learn about redistricting, click on the “Help” tab for a “Glossary” of redistricting terminology.
*Click on the “Help” tab for a step-by-step “Guide to Learning the Features of MyDistrictBuilder.”
Share Your Ideas
*Do you have a question or comment? Do you have a suggestion to improve MyDistrictBuilder? Feel free to email or visit us at Facebook or Twitter.

Screen Control

If you are using Microsoft Internet Explorer you can hold down your Ctrl key and click on the blue area to the right of the title, where you see the yellow circle to the left and by turning the mouse wheel change the screen resolution so you can see more or less on the map.
You can press F11 on your keyboard to toggle Internet Explorer into a mode where the browser headers are hidden till you put your cursor at the top of the page. This will also give you a bigger map.
You can use the white double arrow button in the right and left corners of the map to hide the right and left side bars and see more of the map.

You can click and drag the blue bar at the top of the data grid to expand or contract the grid to see more map or more grid.
By clicking on the white box at the edge of the Key map you can toggle the key map on and off. Clicking anywhere in the key map will move you to that place on the map.

By clicking on the View tab you can go to the sub menu and toggle full screen and normal screen.
You can adjust the size of menus on both sides of the map and on the bottom by clicking and dragging the blue line on the border.

Map Control
You can change your Bing Maps settings to an Aerial or Road based view by clicking the buttons below the top menu. You may also turn Labels on or off.

Layer Control
Notice on the left side of the screen, the “Layers” menu appears with several options. Clicking on the check box of any of these options will allow you to see the Census County, Tract, Block Group, Block, and/or other boundary lines.
The line around the layer name is the same color as what will appear on the map to outline the census layer.
Each boundary option is only visible at a certain zoom level. For example, Block Groups in the picture above can only be seen at zoom level 12 to 15. These default zoom ranges may be edited so that layers may be visible at lower or higher zoom levels.
You can see what zoom level you are at by looking for the number next to the word zoom in the blue title area at the top of the page. The example above shows the “Counties” layer at zoom level 7.

Label Control
Notice on the right side of the screen, the “Region Labels” menu appears with several options. Clicking on the check box next to “isRegionLabelOn” will allow you to turn on different data displays. Clicking on a data option will display a number in whatever layer you have selected.
For example, clicking on “Tpop00” when you have the “Counties” layer selected will show you the total number of people that live in each county according to the 2000 Census.

Shading Control
On the right, lower side of the screen a “Region Fill” menu appears with several options. Clicking on the check box next to “isRegionFillOn” will allow you to turn on different color shadings according to what data you specify.
For example, with the “Counties” layer and check box next to Cen00:Tpop selected, you can adjust the numbers to whatever specification you desire. This will cause counties that match your specified criteria to be shaded with a certain color.
The “Region Label” and “Region Shading” functions can be used simultaneously.

Building Maps
Click the “File” tab and then “New” to start a new House, Senate, Congressional or Custom plan. Once you select one of these options, you will notice your top menu add several new buttons. These are all tools to help you begin building districts.
To save your map, click the “File” tab and then “Save As.” You will then be prompted to choose where to save your map and name it. This will allow you to log off and come back to complete your map at a later time. NOTE: If you are creating a Congressional map, begin your file name with “C.” If you are creating a House or Senate map, begin your file name with an “H” or “S.” Make sure you select the “Local Isolated” button before saving.

Under the “Build” tab, you will notice a row of numbered/colored buttons. These buttons allow you to choose which district you would like to build with.

This group of buttons under the “Build” tab allow you to do several things. Clicking the “D” button will allow you to show or hide the row of district selection numbers. Clicking on the “S” button when you are building a district will show you any “stragglers.” These are pieces of a district that are not connected. The “SD” button will show or hide on the map any districts you have drawn.
You can begin building by choosing a district, that you would like to build with, and by lasso or click. Choosing “Click” will allow you to build by clicking once. Choosing “Lasso” will allow you to select multiple areas of geography at one time. You can build your districts by choosing census county tract, Block Group, or Blocks.

You can also unassign a piece of geography that has been assigned to a district by completing the same steps as if you were preparing to build, but clicking the “UnAssign” button instead of a district button.

If you make a mistake during building, you can undo your last move by clicking on the “Undo” button.
By selecting a district and clicking the “Lock” button, you can make that district unable to be edited. To make the district editable again, simply select the desired district and click “Unlock.”

If you are working on several maps at once, you may copy any district you are working on from one map to another. To do this, select the district you wish to copy and then click the “Copy” button. Then go to your second map and select which district you would like to paste into. Then click “Paste.”

The Grid Control
The data grid at the bottom of the page is automatically populated with information from each district that you create. Like the other menus, the grid can be expanded or contracted by clicking and dragging the border. Each category may also be sorted from highest to lowest or lowest to highest by clicking on the header.
For a complete list of what each heading means, click on the “Help” tab and then “Glossary.”

The data you see in the grid or shading and as labels is reported at different levels of geography. Census blocks are reported by census blocks, VTD’s, block groups, tracts and counties. Election data is reported by precinct. Precinct boundaries change from election to election. In order to project census data onto precincts for a given year or conversely to project election data for a given year into census geography a process is used call ‘areal interpolation’. Central to the concept of areal interpolation is the concepts of
source and target. The source represents a layer of geography for which we have known data. The target represents a layer of geography for which we want to project (or interpolate) unknown data. Interpolation occurs when we take the area in common between a source geography layer (e.g. census geography) and target geography layer (e.g. election geography) and use it to calculate the percentage of data to project onto the target geography. The accuracy of this data can become skewed in small areas, however as you build (aggregate) the data into larger areas these inaccuracies become less skewed. Additionally, inaccuracies can occur along edges of geographical boundaries (e.g. where you may have a high-rise apartment that houses a population that is much different that the surrounding population). Nonetheless, areal interpolation offers a standard approach to estimate data across geographical layers where data is unknown.

Last edited Apr 7, 2011 at 11:22 PM by MyDistrictBuilder, version 4


No comments yet.