Data Layout#
Introduction#
The Congressional District - ZIP Code Database catalogs ZIP codes and counties within the boundaries of each state’s congressional districts. Unlike other databases linking one district to each ZIP code, this one represents real-world combinations. Notably, over 6,000 5-digit ZIP codes span multiple districts. While the database identifies these ZIP codes and their districts, it can’t precisely determine the district for a specific street address in these cases. Additional tools are available for that. The database contains city names, state abbreviations, county info (names and FIPS codes), MSA/PMSA details (if applicable), and congressional districts for nearly 42,000 USPS-defined ZIP codes. This data aids in targeted mailings for campaigns by identifying ZIP codes within desired districts.
Members of the 118th Congress#
The Congressional District ZIP Code Database encompasses a “crosswalk” file with contact details for each member or delegate of the 118th US Congress. This ASCII file provides comprehensive information, including the name, state, district, DC office address, telephone and fax numbers, email form, and website contact info for all 541 Members of Congress. This encompasses 435 members in the House, 6 non-voting delegates, and 100 Senate members.
ZIP codes cross congressional district boundaries#
ZIP codes often intersect congressional district boundaries, with approximately 15 percent of ZIP codes crossing such boundaries. Even six ZIP codes span five congressional districts. This underlines the need for a dedicated database like the Congressional District - ZIP Code Database, which indicates whether a ZIP code crosses a district boundary. If not, the given congressional district applies to all addresses within that ZIP code.
Using ZIP code to find the correct congressional district#
You cannot determine with 100 percent accuracy the correct congressional district for a given address on the basis of the 5-digit ZIP code alone. You need to know whether or not the ZIP code crosses congressional district boundaries. That information comes from the Congressional District - ZIP Code Database. For each 5-digit ZIP code, the Congressional District - ZIP Code Database shows whether that ZIP code crosses a congressional district boundary. If not, then that one congressional district is valid for all addresses within that 5-digit ZIP code. There is no need to check the actual street address in this case.
Using street address to find the correct congressional district
If the 5-digit ZIP code does cross a congressional district boundary, you must use the street address to determine the correct congressional district for any address within that 5-digit ZIP code. In this case, we suggest that you use our companion product Perfect Address to find the correct congressional district using the street address.
Other useful data…#
The Congressional District - ZIP Code Database provides versatile functions, such as identifying ZIP codes within congressional districts and vice versa. It reveals associated city, county, and FIPS code data. The database helps target ZIP codes for voter mailing lists based on district coverage percentage.
Offered as a single file for the entire country with around 64,000 records, it’s updated monthly and includes state info with 2-digit FIPS codes. Data is sourced from the USPS and cross-referenced for accuracy.
The database also features a file with details about current 118th Congress members, including districts, parties, contact info, etc.
The included databases are:
Congressional District ZIP Code Database (CDZ)
Congressional District Database (CDD)
List of Files#
- Fixed length (ASCII)
- FoxPro (DBF)
- ACCDB
- XLSX
- CSV
Layout and Definitions#
Congressional District Database (CDD)#
Full Format Version (allfiles.txt)#
Column Name |
Type |
Definition |
|---|---|---|
ZIP+4 |
char(9) |
A ZIP+4 Code is a 4-digit code appended to a standard 5-digit ZIP that helps the USPS sort, route, and deliver mail more efficiently. |
City Name |
char(28) |
The City Name field identifies the city in which the ZIP+4 lies. This may be the preferred city name or an approved alternate city name. |
City Place FIPS |
char(5) |
The city place FIPS code comes from the Census Bureau Place FIPS file, which does not always agree with US Postal Service naming and spelling for a given place name. Where no matching city Place FIPS code can be determined, the city FIPS code is set to 00000. |
County Name |
varchar(25) |
The County Name field identifies the county in which the particular ZIP+4 lies. |
County FIPS |
char(3) |
The County FIPS Code is a 3-digit field containing the unique numeric identification assigned to the county named by the county name field. |
State Code |
varchar(2) |
The State Code is the USPS 2-character state abbreviation, such as CA for California. |
State FIPS |
char(2) |
The State FIPS code is a 2-digit code assigned by the US Government to uniquely identify each of the 50 states. This code also covers Puerto Rico, Washington DC, US Virgin Islands, and various Pacific territories, which are included with this database for completeness. |
Congressional District |
char(2) |
The Congressional District (CD) field identifies the district of the House of Representatives of the current Congress in which the ZIP+4 code lies. If the state has only a single congressional district this field contains 00. This district matches the location of the ZIP+4, but may differ from the district of the 5-digit ZIP code. |
State Code of ZIP Code |
char(2) |
The State Code of ZIP is the USPS 2-character state abbreviation, such as CA for California. This state code indicates the actual state in which the 5-digit ZIP code (but NOT the ZIP+4) lies. |
Concise Format Version (cddrange.txt)#
Column Name |
Type |
Definition |
|---|---|---|
ZIP |
char(5) |
The 5-digit ZIP code to which the ZIP+4 range belongs. |
ST |
char(2) |
The State Code (ST) is the USPS 2 character state abbreviation, such as CA for California. |
CD |
char(5) |
The CD field identifies the district of the House of Representatives of the current Congress in which the ZIP+4 range lies. If the state has only a single congressional district this field contains400. This district matches the physical location of the ZIP+4 records and spelling for a given place name. Where no matching city Place FIPS code can be determined, the city FIPS code is set to 00000. |
Low |
char(4) |
This is the low end of the ZIP+4 range for the Congressional District. |
High |
char(4) |
This is the high end of the ZIP+4 range for the Congressional District. |
Congressional Membership Crosswalk File (cdlist.txt/cdlist.csv)#
Column Name |
Type |
Definition |
|---|---|---|
ST |
char(2) |
The 2-character USPS State Abbreviation (“CA”, etc.) |
ST FIPS |
char(2) |
The State FIPS field is a 2-digit code assigned by the Federal Government to each of the 50 states and the various territories, such as Puerto Rico, US Virgin Islands, and Washington DC. |
DIST |
char(2) |
The District field is a 2-digit district number assigned to each member of the House of Representatives. |
First |
char(16) |
First Name of Member |
Middle |
char(16) |
Middle name of Member |
Last |
char(21) |
Last Name of Member |
Party |
char(1) |
Party Affiliation |
Address |
varchar(50) |
“The office address is for one of the various congressional office buildings located near the Capitol. For members of the House the last line of the address for mailing purposes is: Washington DC 20515. For members of the Senate the last line of the address for mailing purposes is: Washington DC 20510.” |
Tel |
varchar(12) |
The telephone number is for the Washington DC office of the representative or senator, including area code. Since the area code is always 202, this field can shortened to 7 digits. |
varchar(62) |
This field is a link to the member’s contact web page or email form web page. |
|
Web Site |
varchar(30) |
A link to the members official congressional website. |
Exception File (XXCDIST.txt)#
Column Name |
Type |
Definition |
|---|---|---|
ZIP+4 |
char(9) |
A ZIP+4 Code is a 4-digit code appended to a standard 5-digit ZIP that helps the USPS sort, route, and deliver mail more efficiently. |
City Name |
char(28) |
The City Name field identifies the city in which the ZIP+4 lies. This may be the preferred city name or an approved alternate city name. |
City Place FIPS |
char(5) |
The city place FIPS code comes from the Census Bureau Place FIPS file, which does not always agree with US Postal Service naming and spelling for a given place name. Where no matching city Place FIPS code can be determined, the city FIPS code is set to 00000. |
County Name |
varchar(25) |
The County Name field identifies the county in which the particular ZIP+4 lies. |
County FIPS |
char(3) |
The County FIPS Code is a 3-digit field containing the unique numeric identification assigned to the county named by the county name field. |
State Code |
varchar(2) |
The State Code is the USPS 2-character state abbreviation, such as CA for California. |
State FIPS |
char(2) |
The State FIPS code is a 2-digit code assigned by the US Government to uniquely identify each of the 50 states. This code also covers Puerto Rico, Washington DC, US Virgin Islands, and various Pacific territories, which are included with this database for completeness. |
Congressional District |
char(2) |
The Congressional District (CD) field identifies the district of the House of Representatives of the current Congress in which the ZIP+4 code lies. If the state has only a single congressional district this field contains 00. This district matches the location of the ZIP+4, but may differ from the district of the 5-digit ZIP code. |
State Code of ZIP Code |
char(2) |
The State Code of ZIP is the USPS 2-character state abbreviation, such as CA for California. This state code indicates the actual state in which the 5-digit ZIP code (but NOT the ZIP+4) lies. |
Congressional District-ZIP Code Database (CDZ)#
Column Name |
Type |
Definition |
|---|---|---|
ST_FIPS |
char(2) |
The State FIPS code is a 2-digit code assigned by the US Government to uniquely identify each of the 50 states. This code also covers Puerto Rico, Washington DC, US Virgin Islands, and various Pacific territories, which are included with this database for completeness. |
CDist |
char(2) |
The Congressional District (CDist) field identifies the district of the House of Representatives of the current Congress in which all or some portion of the ZIP code lies. If the ZIP code lies in more than one congressional district, the Multi-district flag for the record is set to “Y”. For those states with only one representative, and for Puerto Rico, US Virgin Islands, Washington DC, Guam, and American Samoa the Congressional District field is set to “00”. If the state code identifies a territory which has no representation in the US Congress (certainPacific territories) this field is blank. See the file cdlist.txt (included with this product) for a full list of the name of each member of Congress, along with the member’s district and Washington office address. |
ZIP |
char(5) |
The ZIP Code field identifies one ZIP code which lies at least partially within the boundaries of the congressional district identified by the congressional district field and at least partially within the boundaries of the county identified by the county name and FIPS fields. Note that portions of this ZIP code may also lie within the boundaries of other congressional districts and/or counties. The ZIP code field is treated as a text field, not a numeric field. This is to prevent the loss of the leading zeroes in certain ZIP codes when the data is imported into a database program. |
Type |
char(1) |
The ZIP Code type field identifies special kinds of zip codes. For normal residential ZIP codes, this field is blank. |
City |
varchar(28) |
The City Name field identifies the one (preferred) city associated with the particular ZIP code and not necessarily the County by the USPS. |
ST |
char(2) |
The State Code (ST) is the USPS 2 character state abbreviation, such as CA for California. |
County |
varchar(25) |
The County Name field identifies a county which contains some or all of the ZIP code identified by the ZIP code field. If the ZIP code lies in multiple counties, the Multi-county flag is set to “Y”. |
FIPS |
char(5) |
The County FIPS Code is a 5-digit field containing the unique numeric identification assigned to the county named by the county name field. The FIPS code is assigned to each county by the US Government. We have combined the 2-digit state FIPS code with the 3-digit county FIPS code to yield a 5-digit code which can be used to uniquely identify each county in the USA. The County FIPS field is also treated as a text field to prevent the loss of leading zeroes. |
Percent |
char(5) |
The ZIP code percent field identifies the percentage of the ZIP code which lies within the common area of the congressional district and the county. This number is not based on area or population, but on actual ZIP+4 address records in the USPS ZIP+4 address database (not included with this database). If the ZIP code lies entirely within the congressional district AND the county, the ZIP code percent value is 100%. |
MSAPMSA |
char(4) |
The MSA/PMSA field contains the Metropolitan Statistical Area code or Primary Metropolitan Statistical Area code, if any, in which the ZIP code lies. The MSA/PMSA code is assigned by the Office of Management and Budget of the US Government. See the file msapmsa.txt (included with this product) for a complete list of all valid MSA/PMSA codes. Note: only ZIP codes defined for “metropolitan” areas have an MSA or PMSA code. Most rural ZIP codes do not have an assigned MSA/PMSA code. |
Multi-cnty |
char(1) |
The Multi-county flag is set to “Y” if the ZIP code lies within multiple counties. If so, then this same ZIP code will appear in some other record in the database. |
Multi-dist |
char(1) |
The Multi-district flag is set to “Y” if the ZIP code lies within multiple congressional districts. If so, then this same ZIP code will appear in some other record in the database. If this flag is blank, you can assume that the congressional district of this record is valid for any address using the ZIP code of this record. Note:
|
Code and Definitions#
Congressional District-ZIP Code Database (CDZ)#
Column Name |
Code |
Definition |
|---|---|---|
Type |
P |
ZIP Code applies only to PO Boxes |
M |
Military ZIP code (APO/FPO) |
|
U |
Unique ZIP Code assigned to one business or organization |
|
Blank |
Normal Residential ZIP Codes |