Phase4_Guide

The Redistricting Data Program

Phase4_Guide

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Collection of Post-2020 Census Congressional
and State Legislative District Plans (Phase 4)
User Guide

Last updated August 2024.

U.S. Census Bureau

2030 RDP Phase 4 Guide

TABLE OF CONTENTS
Part 1

Phase 4 Introduction ........................................................................................... 1

Part 2

Phase 4 Timeline ................................................................................................. 2

Part 3

Phase 4 Submission Materials.............................................................................. 3

1.1

Block Equivalency Files (BEF) ........................................................................................... 3

1.2

Population Totals ............................................................................................................. 4

1.3

State Legislation ............................................................................................................... 4

1.4

Split Block Listing ............................................................................................................. 5

1.5

SLD Names Files ............................................................................................................... 5

1.6

Checklist ........................................................................................................................... 6

Part 4

Relationships between CDs and SLDs and Other Legal Boundaries ....................... 7

Part 5

Submitting Materials ........................................................................................... 8

Appendix A

Using GUPS for Split Block Plans ................................................................... A-1

Suggested Workflow Summary .................................................................................... A-1

Suggested Workflow Detailed ...................................................................................... A-2

A2.1

Install GUPS ............................................................................................................. A-2

A2.2

Start a Project ......................................................................................................... A-2

A2.3

Import your CDs/SLDs ............................................................................................. A-2

A2.4

Symbolize your CD/SLD Layers ............................................................................... A-3

A2.5

Create the Block Splits ............................................................................................ A-4

A2.6

Adjust CDs/SLDs to Match the Block Splits ............................................................. A-5

A2.7

Review Current and Previously Submitted Block Splits .......................................... A-5

A2.8

Repeat the Process for Other CD, SLDU, or SLDL Layers in the Same County........ A-6

A2.9

Run Criteria Review Tool......................................................................................... A-6

A2.10 Export the Project for Submission .......................................................................... A-7
Appendix B

LSAD Codes with Details ............................................................................... B-1

Appendix C

Checklist ...................................................................................................... C-1

Appendix D

File Submission through the Secure Web Incoming Module (SWIM) .............. D-1

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2030 RDP Phase 4 Guide

LIST OF TABLES
Table 1: Timeline for 120th CD and 2026 SLD Plan Collection ........................................................ 2
Table 2: LSAD Codes, Descriptions, and Associated Geographic Entities.................................... B-1
Table 3: Checklist for Phase 4 ...................................................................................................... C-1

LIST OF FIGURES
Figure 1: Congressional District BEF Schema and Example for Connecticut .................................. 3
Figure 2: State Legislative District BEF Schema and Example for Connecticut .............................. 4
Figure 3: SLD Names File Schema and Example for the District of Columbia ................................ 5
Figure 4: Switch To Tool Icon ....................................................................................................... A-2
Figure 5: Import Working File Tool Icon ...................................................................................... A-2
Figure 6: Import Working File Tool Dialog ................................................................................... A-3
Figure 7: Add Vector Data Tool Icon ............................................................................................ A-3
Figure 8: Enabling the CD, SLDU, and SLDL Symbology ............................................................... A-4
Figure 9: Feature Flagging Tool Icon ............................................................................................ A-4
Figure 10: Feature Flagging Tool Dialog....................................................................................... A-4
Figure 11: Modify Area Feature Tool Icon ................................................................................... A-5
Figure 12: Review Block Boundary Tool Icon ............................................................................... A-5
Figure 13: Review Block Boundary Dialog ................................................................................... A-6
Figure 14: Criteria Review Tool Icon ............................................................................................ A-6
Figure 15: Export to ZIP Tool Icon ................................................................................................ A-7

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PART 1

PHASE 4 INTRODUCTION

During Phase 4, as official Redistricting Data Program (RDP) liaisons designated by the
legislative leadership in your state, the District of Columbia (DC), or the Commonwealth of
Puerto Rico (PR), you have the opportunity to submit any newly enacted congressional (CD),
state legislative (SLD), or legislative (DC, PR) district plans to the U.S. Census Bureau. You will
also be provided an opportunity to verify that the Census Bureau has correctly inserted any
newly enacted plans you provide into the Master Address File/Topologically Integrated
Geographic Encoding and Referencing (MAF/TIGER) System.
IMPORTANT:
•

Submission of the 120th CDs and/or the 2026 SLDs is only required if your plans have
changed since our collection of the 119th CDs and 2024 SLDs in 2024.

If the plans for the 120th CDs and 2026 SLDs have not changed, please report that there are no
changes on the certification form and return it to the Redistricting & Voting rights Data Office
(RVDO) 1 at . No other action is necessary.
0F

•

If the plans for the 120th CDs and 2026 SLDs have changed, please report the changes
accordingly on the certification form and email it to the RVDO at . In addition:
o If the new plan(s) is comprised of whole census blocks, review the procedures in this
document to create and submit your new whole block plan(s).
o If the new plan(s) is comprised of split blocks:
 In addition to the whole census block change procedures, review Appendix A for
instructions on using the Geographic Update Partnership Software (GUPS) to submit
split blocks.
 The GUPS and required shapefiles for creating split block plans will not be available until
January 2026. The RVDO will notify you when the software and shapefiles become
available.

•

Once the plan(s) has been submitted, reviewed, and inserted into the MAF/TIGER System, a
verification phase is conducted to ensure that your data were inserted correctly, and our system
reflects the new plan(s).

The RVDO and RDO initialisms are used interchangeably to represent the Redistricting & Voting rights Data Office.
Regardless of the initialism that appears in the RDP materials, or the one spoken by staff involved with the RDP,
the email address remains the primary method of contact for the 2030 RDP.
1

U.S. Census Bureau

2030 RDP Phase 4 Guide

PART 2

PHASE 4 TIMELINE
Table 1: Timeline for 120th CD and 2026 SLD Plan Collection
Item

Timing

States receive Phase 4 invitation

November 2025

States submit new CD/SLD whole block plans to the Census Bureau

November 2025 – April 15, 2026

States submit new CD/SLD split block plans to the Census Bureau

January 2026 – April 8, 2026

Deadline for verification updates

April 30, 2026

Census Bureau releases CD/SLD products to its website

August 2026 – March 2027

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2030 RDP Phase 4 Guide

PART 3

PHASE 4 SUBMISSION MATERIALS

The following materials are detailed in this part of the guide:
1. Block equivalency files (Required).
2. Population totals from the 2020 Census Redistricting Data (P.L. 94-171) Summary File
(Required). Refer to section 1.2 for details.
a. Population totals from any adjusted population base (Optional).
3. State legislation documenting your post-2020 Census boundaries (Required). Refer to section
1.3 for details.
4. Split block listing (Required, if applicable). Refer to section 1.4 for details.
5. SLD names files (Optional, if applicable). Refer to section 1.5 for details.
6. Checklist (Optional). Refer to section 1.6.

1.1

Block Equivalency Files (BEF)
•

A separate file is required for each entity type; one for CDs and one for SLD by whole blocks.
Include the state name or abbreviation and the district type, e.g., CD120 or SLD26, in the file
name. For example, CD120_MD.txt or SLD26_VA.txt.

•

The files must be comma-delimited text format and formatted as shown in Figure 1 for CDs and
in Figure 2 for SLDs.

Figure 1: Congressional District BEF Schema and Example for Connecticut

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2030 RDP Phase 4 Guide

Figure 2: State Legislative District BEF Schema and Example for Connecticut

Note: These files should contain a record for every 2020 Census tabulation block in your state,
including all water blocks. If water blocks are not assigned to a specific district, they should be
assigned a “ZZ” code for unassigned congressional districts and a “ZZZ” code for unassigned
state legislative districts. If ZZ and ZZZ codes are not assigned by the state, they will be applied
by the Census Bureau during processing of the file.

1.2

Population Totals

To assist in verifying the accuracy of the boundaries we inserted into the MAF/TIGER System,
please provide:
•

A list of the official 2020 Census population totals by district, from the P.L. 94-171 Redistricting
Data, for each submitted CD, SLD Upper (SLDU), and SLD Lower (SLDL) plan.

•

A list of any state-adjusted 2020 Census population totals by district for each submitted CD,
SLDU, and SLDL plan (if applicable). (Optional).

•

A list of the counties or county equivalents that are split by a CD, SLDU, or SLDL boundary (if
applicable) and the 2020 Census population associated with each district’s part in those
counties. (Optional).

1.3

State Legislation

State legislation documenting the CD and/or SLD boundaries is required. Two examples include:
•

Enacted legislation establishing the districts (congressional or state).

•

Court order establishing the districts (congressional or state).

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1.4

Split Block Listing

The Census Bureau cannot tabulate 2020 Census data for split blocks. If your CD and/or SLD
boundaries DO NOT follow 2020 Census tabulation blocks the following materials are also
required:
•

A whole block BEF, where any split block is assigned to the single most appropriate district that
should be used when tabulating 2020 Census data.

•

A list of all 2020 Census tabulation blocks that include more than a single CD or SLD, i.e., the split
blocks, the CD or SLD codes shared by those blocks, and the single CD or SLD the state, DC, or PR
wishes to assign to that block for 2020 Census data tabulation purposes. See the previous bullet.

•

Block split shapefile(s) created using GUPS. Refer to Appendix A for guidance on this
requirement.

1.5

SLD Names Files

Phase 4 allows for the submission of SLD names. If SLD names are not provided the district
number will be used as the name. If you wish to supply this information, please provide:
•

Two separate files, one for the upper chamber (SLDU) and one for the lower chamber (SLDL).

•

Include the state, or state-equivalent, name or abbreviation and either “house”, “senate”, or
“ward” in the file name. For example, DC_ward_names.txt or MD_house_names.txt.

•

The files must be comma-delimited text format and formatted as shown in the figure below.

Figure 3: SLD Names File Schema and Example for the District of Columbia

The MAF/TIGER System uses a combination of Names and Legal/Statistical Area Description
(LSAD) codes for storing standardized and repeated prefixes and suffixes for congressional and
state legislative district names. In reviewing your submission, we may adjust your supplied
name and apply these LSAD codes for naming purposes. The RVDO asks you to review the LSAD
codes and descriptions and conform your naming convention to one of the existing LSADs when
possible. See Appendix B for a list of LSADs.
If none of the LSADs match your naming convention, please include your names in the NAME
field. The RVDO will contact you during our review if we have questions about the names.

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2030 RDP Phase 4 Guide

1.6

Checklist

Though optional, use of the checklist ensures all the necessary information is provided and
allows the RVDO to confirm we have received all the information you intended to submit. It is
available in Appendix C, and from the Phase 4 portion of the Redistricting Data Program
Management website.

U.S. Census Bureau

2030 RDP Phase 4 Guide

PART 4

RELATIONSHIPS BETWEEN CDS AND SLDS AND
OTHER LEGAL BOUNDARIES

As the decade proceeds, there is a need to manage any permanent relationships that CDs and
SLDs have to other governmental unit boundaries like incorporated places and county
subdivisions.
This geographic relationship information was collected as a part of the 118th Congressional and
2022 State Legislative District collection. For more information on the relationships for your
state, of if there are changes to your state’s relationships, please contact the RVDO at
301-763-4039 or at .

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2030 RDP Phase 4 Guide

PART 5

SUBMITTING MATERIALS

To create submission files, follow the instructions below that apply to your submission.
For all participants, please zip your files into a single zip file named “cdsld26__return”,
where is the two-character state, DC, or PR abbreviation. This .zip file should include
the required files listed below and any optional files that are applicable.
•

Block equivalency file (Required).

•

Population totals (Required).
o Adjusted population totals (Optional).

•

State legislation documenting the post-2020 Census boundaries (Required).

•

SLD Names Files (Optional).

•

Certification Form (Required).

•

Checklist (Optional).

For participants submitting split block plans, in addition to the submission zip file described
above, include the zip file(s) that GUPS generates. Locate the file(s) on the machine used to
prepare your submission beneath the directory on the hard drive named
“\GUPSGIS\gupsdata\BBSP26\”. The file name is structured as “bbsp26__return.zip”
where STCOU represents the five-digit InterNational Committee for Information Technology
Standards (INCITS) codes, formerly the Federal Information Processing Standards (FIPS) code,
for the state and county 2. Submit the GUPS generated zip file(s) as a separate zip file.
1F

There will be a submission file for each county that contains a CD, SLDU, or SLDL block split. Do
not zip these separate files into a single file; instead, add them as individual zip file attachments
to your submission. Appendix A provides the details for using GUPS to create block split plans.
IMPORTANT:

The Block Boundary Suggestion Program (BBSP) begins in January 2026 and there is the
possibility that you will be submitting split block and BBSP updates for the same
submission. If this occurs, please contact the RVDO at 301-763-4039 or
to discuss coordinating these updates or if you have any other
questions or concerns.

The RDP uses the Secure Web Incoming Module (SWIM) to accept both whole block and split
block submissions. For instructions on SWIM, refer to Appendix D.

Refer to the Census Bureau’s ANSI and FIPS Codes webpage for more information on the change from FIPS to
INCITS.
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2030 RDP Phase 4 Guide

APPENDIX A

USING GUPS FOR SPLIT BLOCK PLANS

GUPS should only be used if CD, SLDU, or SLDL boundaries split census blocks. The file(s)
created using GUPS must be submitted with the zip file created by all participants described in
Part 5. That file specifically includes the whole block BEF and the split block listing.
This work is completed on a county basis and must be repeated for each layer that uses the
split(s), e.g., CD, SLDU, and/or SLDL, in the same county-based project. Once an edge is flagged
as a block split, it cannot be flagged again. For example, if a block split serves as a boundary for
the CD, SLDU, and SLDL, only create the block split for one district i.e., the CD, SLDU or SLDL. It
can then serve as the block split for any other district; however, you will have to import the
other district type’s BEF and manually adjust their areas to match the new boundary. Please
contact our office to discuss coordinating the CD/SLD block splits and your BBSP submission.

Suggested Workflow Summary

There is no specific CD/SLD Update module listed in GUPS. Use the Block Boundary Suggestion
Project module selection. Details on each of the workflow steps summarized below are found in
Appendix A2.
1. Install GUPS.
2. Start a project. Open the State/County in GUPS. Block splits are created on a county basis. The
RVDO is unable to create a statewide CD/SLD shapefile with block splits in GUPS at this time.
3. Import your CDs/SLDs. In GUPS, BEFs are called tabular equivalency files (TEF)s. Import your BEF
using the Import Working File tool. This tool conflates your BEF to 2020 census tabulation
blocks. Once the BEF is imported, review the CDs or SLDs and make the block splits and spatial
adjustments. A statewide BEF can be supplied to the import tool, and GUPS will extract the
county that you are working in.
4. Symbolize your CD/SLD layers.
5. Create the block splits. If needed, use the linear feature tool to digitize new edges or use
existing edges and the block boundary flagging tool to create and mark the block splits.
6. Adjust CDs/SLDs to match the block splits. Use the Modify Area Feature Tool to adjust CDs
and/or SLDs to the block splits. The RVDO will conduct their review and contact you if there are
questions.
7. Review current and previously submitted block splits. Review your block splits to ensure that
they are still needed as CD/SLD boundaries.
8. Repeat process for other layers (CD/SLDU/SLDL) within the same county (if applicable).
9. Run Quality Control Check. Run the Criteria Review Tool to ensure that the CDs and SLDs are
wall-to-wall within the county and validate any discontiguous districts, within the working
county.
10. Export the project for submission. Use the Export to ZIP Tool, specifically the Export for Census
option, to export the project for submission to the Census Bureau.

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2030 RDP Phase 4 Guide

A-1

Suggested Workflow Detailed

The detailed workflow in this appendix outlines the procedures for creating block splits for
submission as part of your plan. Additional information on GUPS functionality is often referred
to in these instructions and can be found in the BBSP GUPS Standalone Guide located on the
BBSP portion of the Redistricting Data Program Management website.

A2.1 Install GUPS
You must use the most current GUPS version because it includes all the functionality needed to
make the CD/SLD updates. It will be available here in early January. If you experience issues
installing GUPS, please contact the RVDO at 301-763-4039 or .

A2.2 Start a Project
1. After launching the software, select the Block Boundary Suggestion Project, and then your State
and County.
2. When prompted to Select Data Folder, Directory, or Location, we recommend that you select
Census Web. This will automatically download the partnership shapefiles required for your
submission into the project.
3. As GUPS loads the data, it unzips and copies the files to a folder that it creates on your
computer’s home directory during the installation process. For this update cycle, it is
C:\Users\\GUPSGIS\gupsdata\BBSP26\shape. GUPS then loads the shapefiles into
the project. For more information, refer to the previously linked BBSP GUPS Standalone Guide.
4. Change the style from BBSP to VTD using the Switch To Tool. This will shift the style from block
boundaries to features such as roads, rivers, and rails and the CD/SLD Block Split. For more
information on this tool, refer to the Menu, Standard Toolbar, and BBSP Toolbar section in the
BBSP GUPS Standalone Guide.

Figure 4: Switch To Tool Icon

A2.3 Import your CDs/SLDs
The Import Working File Tool allows you to import a BEF or shapefile into your GUPS project.
Once imported, it will be become the active CD, SLDU, or SLDL layer that you can edit to
become your submission. It will replace the current CD, SLDU, or SLDL layer and cannot be
undone, however, you can use this tool to replace the active layer and restart the project if
needed.

Figure 5: Import Working File Tool Icon

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A-2

This process must be repeated for each layer that includes split blocks: CD, SLDU, and SLDL
(where applicable) and can be used for importing a shapefile.
1. Select the Import Working File tool.
2. From the dialog window that opens, select the option of Import Tabular Equivalency File (TEF) or
Import Shapefile.

Figure 6: Import Working File Tool Dialog

3. Map the fields in your BEF or your shapefile to the fields in GUPS.
4. GUPS will conflate the BEF or shapefile to the MAF/TIGER System census tabulation blocks. This
may take a few minutes.
5. For more information on this task, refer to the Menu, Standard Toolbar, and BBSP Toolbar
section in the BBSP GUPS Standalone Guide.
6. Optional: Adding a reference shapefile (vector layer). This tool allows you to bring a shapefile
into the project that can be used as a reference to determine which areas need to be split. Using
Add Vector Layer does not bring the shapefile into the project as an editable layer.
a. To import the shapefile as an editable layer, use the previously described Import Working
File tool but select Import Shapefile instead of Import Tabular Equivalency File. Refer to the
Manage Layers Toolbar section in the BBSP GUPS Standalone Guide.

Figure 7: Add Vector Data Tool Icon

A2.4 Symbolize your CD/SLD Layers
1. Right-click on the cd_STCOU, sldu_STCOU, or sldl_STCOU layer in the Layer pane.
2. Select GUPS Layer.
3. Select Load , , or style as depicted in Figure 8. The selected districts are symbolized as the styles
are programmed in GUPS.

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A-3

Figure 8: Enabling the CD, SLDU, and SLDL Symbology

A2.5 Create the Block Splits
Use the Feature Flagging Tool to flag either existing or new edges as block splits.

Figure 9: Feature Flagging Tool Icon

1. Navigate to the edge that you need to flag.
2. Select the Feature Flagging Tool and then select the edge.
3. From the dialog window that opens, select CD/SLD Block Split for the Action. This assigns a value
of BBSP_2030=S to the edge and the edge will now be represented by a green dashed line.
4. If you need to remove the block split, select the Feature Flagging Tool, select the edge, and then
select NULL under Actions. This will remove the value from the edge, and it will not be held as a
CD/SLD Block Split.

Figure 10: Feature Flagging Tool Dialog

5. Optional: Add Linear Features. If you need to add an edge to create your block split, this tool
allows you to digitize the edge that you need to use as the block split. It is important to note,
there may be an existing edge in the MAF/TIGER System which is not a block boundary but can
be used to split the block, rather than digitizing a new edge. We ask that you not digitize edges
within 7.5 meters of an existing edge.
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A-4

a. Any edges that you add as block splits will need to be flagged as block splits in a separate
action, as described in this section, and you will have to adjust the CD/SLDs to match the
new edges. For more information on how to add a linear feature, refer to the Block
Boundary Suggestion Flagging section in the BBSP GUPS Standalone Guide.

A2.6 Adjust CDs/SLDs to Match the Block Splits
To adjust the CD/SLD boundary to match the block split, especially if you added a new edge,
you must adjust the CD/SLD area features themselves using the Modify Area Feature Tool.

Figure 11: Modify Area Feature Tool Icon

1.
2.
3.
4.
5.
6.

Select the Modify Area Feature Tool.
From the dialog window that opens, select the Geography from the dropdown menu.
Select the CD/SLD to modify.
Select the face(s) on the map to add to the CD/SLD to make it match the new boundary.
Select the Add Area button to add the faces to the CD/SLD.
Repeat the process as needed for each CD/SLD.

For more information on how to edit area features, refer to the Area Landmark Review section
in the BBSP GUPS Standalone Guide.

A2.7 Review Current and Previously Submitted Block Splits
Use the Review Block Boundary Tool to review your newly created block splits.

Figure 12: Review Block Boundary Tool Icon

1. Select the Review Block Boundary Tool.
2. From the dialog window that opens, select CD/SLD from the Category dropdown menu. This will
list all the block splits applied within the county. It is important to ensure that the block splits
and the CD/SLD boundaries align.
3. Use the arrows to navigate through the list. Selecting the Verify Split button will remove the
edge from the list until you reopen the tool. This is not a necessary step but may assist with
keeping track of what you have and have not reviewed. Selecting the Null button will remove
the CD/SLD Block Split flag.

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2030 RDP Phase 4 Guide

A-5

Figure 13: Review Block Boundary Dialog

4. Ensure each block split is in the correct location and the appropriate CD and SLD boundaries
match the split.
5. The RVDO will contact you with information and materials for reviewing previously submitted
block splits.

A2.8 Repeat the Process for Other CD, SLDU, or SLDL Layers in the Same County
If applicable, to complete your work, repeat the steps outlined in the proceeding A2 appendices
for other layers, e.g., CD, SLDU, or SLDL, in the same county.

A2.9 Run Criteria Review Tool
When all updates are complete for the county, run the Criteria Review Tool to ensure all faces
in the county have CD/SLD coverage. The tool will alert you to unassigned faces and any
discontiguous CDs or SLDs in the county. Unassigned faces must be fixed before exporting for
submission. We do not require correction of discontiguous CDs or SLDs. For further assistance
with the Criteria Review Tool, please contact the RVDO at 301-763-4039 or at
.

Figure 14: Criteria Review Tool Icon

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A-6

A2.10 Export the Project for Submission
After resolving problems uncovered from running the Criteria Review Tool, execute the Export
to ZIP Tool and select the Export for Census option. This creates the required shapefiles that are
needed by the Census Bureau for processing the CD/SLD block splits and packages the data in a
.zip file. For more information on how to the Export to ZIP Tool works, refer to the Submitting
Updates to the Census Bureau section in the BBSP GUPS Standalone Guide.

Figure 15: Export to ZIP Tool Icon

Appendix D describes how to submit the file to the Census Bureau.

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A-7

APPENDIX B

LSAD CODES WITH DETAILS

The following table summarizes the LSAD codes mentioned in section 1.5.
Table 2: LSAD Codes, Descriptions, and Associated Geographic Entities
LSAD Code

LSAD Description

Associated Geographic Entity

NULL

Congressional District, State Legislative District
(Upper and Lower Chamber)

Congressional District (at Large) (actual text)

Congressional District

Congressional District (prefix)

Congressional District

Resident Commissioner District (at Large)
(actual text)

Congressional District

Delegate District (at Large) (actual text)

Congressional District

No Representative (actual text)

Congressional District

State Representative District (prefix)