BAS State Certification How-to Guide

Boundary and Annexation Survey
State Certification How-to Guide
Instructions for Participating in the Boundary and Annexation Survey State Certification
Program

Last updated January 2025.

U.S. Census Bureau

Boundary and Annexation Survey (BAS) State Certification How-to Guide

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TABLE OF CONTENTS
Introduction ......................................................................................................................... iv
A.

BAS State Certification Program ......................................................................................iv

B.

Contact Us ........................................................................................................................iv

C.

Resources .........................................................................................................................iv

Chapter 1 State Laws ........................................................................................................... 1
Chapter 2 BAS State Certification Materials ......................................................................... 2
2.1

Accessing Materials ......................................................................................................... 2

2.2

State Certification Listings ............................................................................................... 2

Chapter 3 Reviewing the Listings ......................................................................................... 3
3.1

Action Codes .................................................................................................................... 3

3.2

List 1: Governments that Disincorporated, Became Inactive, or Ceased to Exist ........... 3

3.2.1 Instructions to Review List 1 ....................................................................................... 4
3.3

List 2: Legal Boundary Changes ....................................................................................... 5

3.3.1 Instructions to Review List 2 ....................................................................................... 7
3.4

List 3: Incorporated Places ............................................................................................... 8

3.4.1 Instructions to Review List 3 ....................................................................................... 9
3.5

List 4: Minor Civil Divisions ............................................................................................ 10

3.5.1 Instructions to Review List 4 ..................................................................................... 11
Chapter 4 Submit Updates to the Census Bureau ............................................................... 12
4.1

Troubleshooting SWIM .................................................................................................. 13

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LIST OF TABLES
Table 1: Action Codes and Descriptions ......................................................................................... 3
Table 2: List 1 Data File Field Descriptions ..................................................................................... 4
Table 3: List 2 Data File Field Descriptions ..................................................................................... 6
Table 4: List 3 Data File Field Descriptions ..................................................................................... 9
Table 5: List 4 Data File Field Descriptions ................................................................................... 11

LIST OF FIGURES
Figure 1: List 1 Example .................................................................................................................. 4
Figure 2: List 2 Example .................................................................................................................. 5
Figure 3: List 3 Example .................................................................................................................. 8
Figure 4: List 4 Example ................................................................................................................ 10

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INTRODUCTION
The U.S. Census Bureau conducts the Boundary and Annexation Survey (BAS) every year to
update legal boundaries, names, and the status of all governments. The Census Bureau uses
this boundary information for data collection, tabulation, and dissemination for the decennial
census, American Community Survey, Population Estimates Program, and many other censuses
and surveys.

A.

BAS State Certification Program

The Census Bureau conducts the BAS State Certification Program to review and certify updates
sent through BAS. As part of the BAS State Certification Program, the Census Bureau compiles
listings of all general-purpose local governments in each state that reported updates during the
previous BAS cycle and distributes them to a governor-appointed State Certifying Official (SCO).
If state laws require governments to report boundary updates to the state, the SCO is
responsible for reviewing the listings and certifying that the information is correct. This
program ensures that the Census Bureau’s inventory of governments is accurate and that the
boundary changes reported to BAS comply with state laws.

B.

Contact Us

If assistance is required in preparing a BAS State Certification Program submission, contact the
Census Bureau at or 1-800-972-5651.

C.

Resources

BAS State Certification Program materials and additional resources are available on the BAS
State Certification website at:
.

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CHAPTER 1

STATE LAWS

The SCO is responsible for understanding the laws in their state that pertain to legal boundary
changes, new incorporations, and disincorporations since this will determine the extent to
which the Census Bureau will accept changes to the BAS State Certification listings. Some states
require general-purpose local governments to report any legal actions causing changes to their
boundaries to a designated state agency. If such laws are in effect, the SCO should have access
to a complete boundary change file through the state government, which they may use to
compare with the Census Bureau listings.
In states that have laws requiring boundary changes to be reported to a state agency, the SCO
may pursue any of the actions described in Table 1.
In states that do not require boundary changes to be reported to a state agency, the SCO does
not need to submit the edited listings to the Census Bureau. However, if the SCO does have
access to a state-level boundary change file, they may use it to certify or add missing records to
the BAS State Certification listings.
In most cases, the Census Bureau will accept edits to legal boundary changes. However, the
Census Bureau will not add or remove legal changes until the changes are confirmed by the
government affected by the change.
A list of state annexation reporting laws can be found here:
.

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CHAPTER 2

BAS STATE CERTIFICATION MATERIALS

All BAS State Certification materials, including the listings for review and this how-to guide can
be found on the BAS State Certification website.

2.1

Accessing Materials
1. On the BAS State Certification website, go to the section of the page that reads, “Download BAS
State Certification Materials.”
2. In the “Select a Geography” drop-down box under “Choose a State to View,” select the state the
SCO is responsible for reviewing.
3. Upon selection of the state name, the website directs to a File Transfer Protocol (FTP) site.
Download the contents of the folder. These are the listings that the SCO will review for the BAS
State Certification Program.

2.2

State Certification Listings

Depending on the state, the SCO will be responsible for reviewing up to four listing files:
•

List 1–Governments reported to the Census Bureau that have disincorporated, become inactive,
or otherwise ceased to exist. This listing is only available if a deleted government was reported
to the Census Bureau during this year’s BAS.

•

List 2–Reported legal boundary changes (annexations, deannexations/detachments, etc.) to
active incorporated places within the state as reported through the most recent BAS.

•

List 3–All governmentally active and inactive incorporated places in the state, according to the
Census Bureau’s records as reported through the most recent BAS.

•

List 4–All governmentally active and inactive minor civil divisions (MCDs) in the state, according
to Census Bureau’s records as reported through the most recent BAS. This list is only provided
for states with MCDs.

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CHAPTER 3

REVIEWING THE LISTINGS

This section describes each type of listing file and explains how to review each in the program
materials.

3.1

Action Codes

For each record in a listing file, the SCO will input an action code into the ”Cert.” column. All
action codes are defined in the table below:
Table 1: Action Codes and Descriptions
Action Code
C

Certify. The SCO certifies that the information for the record is
complete, accurate, and conforms to applicable state laws.

A

Add. The SCO adds a record from the state’s file that is missing from the
listing.

R

Reverse. The SCO requests to remove an invalid record from the listing.

E

Edit. The SCO edits the attribute information for an existing record in
the listing.

X

Duplicate Entry. The SCO indicates that the record is a duplicate of
another record in the listing.

3.2

Description

A blank field means there are no actions for the record. The Census
Bureau will continue to maintain the record and its current attribute
information.

List 1: Governments that Disincorporated, Became Inactive, or Ceased to
Exist

The List 1 data file (Figure 1) contains the names of all governments in the state that have
disincorporated, became inactive (no longer have officers, collect revenue, or conduct
governmental activities), or otherwise ceased to exist as reported through the most recent BAS.
Table 2 provides an explanation of the fields in the data file.

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Figure 1: List 1 Example
Table 2: List 1 Data File Field Descriptions
Column

Field Name

A

Place Name and LSAD

Government’s name and expanded legal/statistical area description.

B

County

County or counties in which the government is located.

C

Effective Date

The date on file for when the government disincorporated, became
inactive, or otherwise ceased to exist.

D

Effective Date Update

Will be initially blank so the SCO can provide edits to the data in the
Effective Date field without overriding original data.

E

Cert.

Will be initially blank so the SCO may certify the records as correct and
complete.

F

Memo

Will be initially blank so the SCO may include any notes regarding a
certain record.

3.2.1

Description

Instructions to Review List 1

Review the List 1 data file to ensure that it provides a complete and correct inventory of all
governments that have disincorporated, become inactive, or otherwise ceased to exist as
reported through the most recent BAS.
1. For all records that are correct, complete, and conform to applicable state laws, enter a ”C” in
the Cert. field.
2. If there is a government that disincorporated, became inactive, or otherwise ceased to exist and
is missing from the data file:
a. Add a new row at the bottom of the data file. Enter the missing government’s name and
the entity type (such as town, township, city, etc.) under the Place Name and
Legal/Statistical Area Description (LSAD) field.
b. Enter the date the government disincorporated, became inactive, or otherwise ceased
to exist into the Effective Date Update field.
c. Provide an explanation in the Memo field.
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3.

4.

5.

6.

3.3

d. Enter an ”A” in the Cert. field. This will inform the Census Bureau that an additional
government should be added to the list of deleted governments.
If any government is listed in error:
a. Enter an ”R” in the Cert. field to notify the Census Bureau that this government should
be removed from the list of deleted governments.
b. In the Memo field, provide an explanation why the government should be removed.
If the Effective Date of the government is incorrect:
a. Enter the correct date the government ceased to exist in the Effective Date Update field.
b. Enter an ”E”’ in the Cert. field to notify the Census Bureau that the Effective Date must
be edited in the list of deleted governments.
If any government is duplicated:
a. Enter an ”X” in the Cert. field to inform the Census Bureau that this government is a
duplicate of another government.
b. In the Memo field, indicate the duplicate ID.
Upon completion of review of the List 1 data file, the SCO certifies the statement at the bottom
of the file by typing their full name, title, and the date of concurrence below the provided
statement.

List 2: Legal Boundary Changes

The List 2 data file (Figure 2) provides an inventory of legal boundary changes to active
incorporated places within the state that were reported to BAS. Table 3 provides an
explanation of the fields in the data file.

Figure 2: List 2 Example

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Table 3: List 2 Data File Field Descriptions
Column

Field Name

Description

A

Place Name and
LSAD

Government’s name and expanded legal/statistical area description.

B

FIPS Place Code

Federal Information Processing Series (FIPS) code for the place.

C

Action

Lists whether the boundary change is an annexation, detachment, or other
type of action.

D

Action Update

Will be blank so the SCO may provide edits to the data in the Action field
without overwriting original data.

E

Authorization Type

Lists the type of legal authorization that effected the change.

F

Authorization Type
Update

Will be blank so the SCO may provide edits to the data in the Authorization
Type field without overwriting original data.

G

Local Number

The identification number of the legal document that recorded the
authorization effecting the change to the boundary.

H

Local Number
Update

Will be blank so the SCO may provide edits to the data in the Local Number
field without overwriting original data.

I

Local Effective Date

Lists the effective date of each action. (Note that there may be a difference
between the effective date of actions on this list and the effective date in
the state’s records because the Census Bureau’s records contain a locally
reported date.)

J

Local Effective Date
Update

Will be blank so the SCO may provide edits to the data in the Local Effective
Date field without overwriting original data.

K

Secondary Effective
Number

The state legal action number identifying the legal document that recorded
the authorization effecting the change to the boundary (if applicable).

L

Secondary Effective
Number Update

Will be blank so the SCO may provide edits to the data in the Secondary
Effective Number field without overwriting original data (if applicable).

M

Secondary Effective
Date

Lists the effective date of each state legal action.

N

Secondary Effective
Date Update

Will be blank so the SCO may provide edits to the data in the Secondary
Effective Date field without overwriting original data.

O

Acreage

Lists the reported acreage of the affected territory.

P

Acreage Update

Will be blank so the SCO may provide edits to the data in the Acreage field
without overwriting original data.

Keying Date

Lists the date that the record was entered into the Census Bureau’s Master
Address File/Topologically Integrated Geographic Encoding and Referencing
(MAF/TIGER) System. The keying date may be used to research boundary
changes on the Census Bureau’s maps.

Q

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Column

Field Name

Description

R

Cert.

Will be initially blank so the SCO may certify the records as correct and
complete. (See Table 1.)

S

GCATOID

Field used internally to identify the change to the government.

T

Will be blank so the SCO may provide additional information about the
record if necessary.

3.3.1

Instructions to Review List 2

Review the List 2 data file (Figure 2) to verify that:
•

Each legal boundary change was submitted in accordance with applicable state law.

•

The place name, action, authorization type, local number, local effective date, acreage, and if
applicable, secondary effective number and secondary effective date, shown for each record is
correct.

•

The Census Bureau’s list is complete as reported through the most recent BAS.

When reviewing the List 2 data file, the SCO may determine that a record(s) in the Census
Bureau’s data file does not match the state’s records. If this occurs, research if specific
attributes of the change are incorrect or if the boundary update was not completed in
accordance with state law(s).
Note: Some places provide the Census Bureau with the legal documentation along with maps of
boundary changes. To view the legal documentation for a change, contact the Census Bureau. In
the email, specify the government that the change affected and the attribute information
associated with the change in List 2. The Census Bureau will research to determine if there is
supplemental information for this change.
1. If a boundary change was accomplished in accordance with state law and the attribute data is
correct and complete, enter a ”C” in the Cert. field.
2. If a boundary update is missing from the Census Bureau’s records:
a. Then in a blank row at the bottom of the spreadsheet enter the following information:
i. Enter the name and type of the government where the change occurred in the Place
Name and LSAD field, respectively.
ii. Enter “annexation” or “deannexation” into the Action Update field.
iii. Enter “ordinance,” “resolution,” “local law,” “state-level action,” or “other” into the
Authorization Type Update field.
iv. Enter the legal document number into the Local Number Update field.
v. Enter the effective date into the Local Effective Date Update field.
vi. Enter the acreage into the Acreage Update field (if available).
vii. Type the state legal action number into the Secondary Number Update field and
enter the effective date of the state legal action into the Secondary Effective Date
Update field (if applicable).
viii. Enter an ”A” in the Cert. field to inform the Census Bureau that an additional
boundary change should be added to the Census Bureau’s database.
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3. If a boundary change was not accomplished in accordance with applicable state law, the SCO
may complete one of the two actions below:
a. Leave the Cert. field blank, which will indicate that the state government does not
certify the change, but the SCO does not wish to reverse the change at this time.
b. Enter an ”R” in the Cert. field. In the blank cell to the right of the Cert. field, note the
reason as well as any additional information about the reversal.
4. If a portion or all the attribute data for the boundary change is incorrect:
a. Type the correct data in the field to the right of the incorrect data. For example, if the
information in the Action field is incorrect, type the correct information in the Action
Update field to the right of the Action field. If the date in which the change is effective is
incorrect, enter the correct date in the Local/Secondary Effective Date Update field.
Blank update fields are also provided if the SCO needs to change the Authorization Type,
Number, and Acreage information.
b. Enter an ”E” in the Cert. field to notify the Census Bureau that a portion or all the
attributes for this record must be edited.
5. If a boundary update is a duplicate of an already existing boundary change:
a. Enter an ”X” in the Cert. field.
6. Upon completion of review of the List 2 data file, the SCO certifies the statement at the bottom
of the file by typing their full name, title, and the date of concurrence below the provided
statement.

3.4

List 3: Incorporated Places

The List 3 data file (Figure 3) shows the names of all active and inactive incorporated places in
the state according to the Census Bureau’s records. An active incorporated place is one that has
officials (elected or appointed) and has the legal capacity to raise revenues and conduct general
governmental activities. Table 4 provides an explanation of each of the fields in the data file.

Figure 3: List 3 Example

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Table 4: List 3 Data File Field Descriptions
Column

Field Name

Description

County Name

The county or county equivalent where each incorporated place is
located.

B

Place Name and LSAD

Lists the places in alphabetical order within a county. If a place exists in
multiple counties, it will be listed under each county in which it is
located. The LSAD is the expanded legal/statistical area description, such
as city, town, village, etc.

C

Part Flag

If the government is located within multiple counties, this field will be
populated by the letter “P” otherwise this field will be blank.

D

FS

Lists the functional status (FS) of the government. Refer to
for a list of the FS codes.

E

FS Update

Will be initially blank so the SCO may provide edits to the information in
the FS field without overwriting original data.

F

Cert.

Will be initially blank so the SCO may certify the records as correct and
complete.

G

Memo

Will be initially blank so the SCO may include notes.

A

3.4.1

Instructions to Review List 3

Review the List 3 data file (Figure 3) to ensure that it provides a complete and correct inventory
of all incorporated places that were governmentally active or inactive.
If a place is in multiple counties in the state’s records, review the file to ensure that it is listed
under each applicable county. Places that occur in multiple counties in the MAF/TIGER System
will have “P” entered in column C (Part Flag) of the data file.
1. For all records that are deemed to be correct and complete enter a “C” in the Cert. field to
certify the record.
2. If a place is missing from the data file:
a. In a blank row at the bottom of the data file, enter the following information:
i. Enter the place’s county name in the County Name field.
ii. Enter the place’s name and entity type in the Place Name and LSAD field.
iii. Enter “active” or “inactive” in the FS field.
iv. Enter the effective date when the place legally incorporated in the Memo field.
b. Enter an ”A” in the Cert. field to inform the Census Bureau that this place should be
added to the MAF/TIGER System.
Note: If the place exists in two or more counties, type all the county names, separated by commas,
into the County Name field.

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3. If a place is no longer incorporated:
a. Provide the effective date of the status change in the Memo field.
b. Enter an ”R” in the Cert. field to notify the Census Bureau that the place should be
removed from the MAF/TIGER System.
4. If the functional status of a place has changed:
a. Enter the correct functional status in the FS Update field.
b. Enter the effective date of the status change in the Memo field.
c. Enter an ”E” in the Cert. field to notify the Census Bureau that the functional status
must be edited in the MAF/TIGER System.
5. Upon completion of review of the List 3 data file, the SCO certifies the statement at the bottom
of the file by typing their full name, title, and the date of concurrence below the provided
statement.

3.5

List 4: Minor Civil Divisions

The List 4 data file (Figure 4) shows the names of all active and inactive MCDs in the state
according to the Census Bureau’s records. An active MCD operates as a government, has
elected or appointed officials, and has the legal capacity to raise revenues and conduct general
governmental activities. States that do not have MCDs will not receive the List 4 data file. See
the BAS State Certification website for a list of states that have MCDs. Table 5 provides an
explanation of the fields in the data file.

Figure 4: List 4 Example

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Table 5: List 4 Data File Field Descriptions
Column

Field Name

Description

A

County Name

The county where each government is located.

B

MCD Name and LSAD

Lists MCDs in alphabetical order within the state. The LSAD is the expanded
legal/statistical area description, such as town or township.

C

FS

Lists the functional status (FS) of the government. Refer to

for a list of the FS codes.

D

FS Update

Will be initially blank so the SCO may provide an updated functional status
without overwriting original data in the FS field.

E

Cert.

Will be initially blank so the SCO may certify the records as correct and
complete.

F

Memo

Will be initially blank so the SCO may include any notes regarding the record.

3.5.1

Instructions to Review List 4

Review the List 4 data file (Figure 4) to ensure that it provides a complete and correct inventory
of all MCDs that were governmentally active or inactive.
1. For all records that the SCO deems to be correct and complete enter a ”C” in the Cert. field to
certify the record.
2. If a government is missing from the data file:
a. In a blank row at the bottom of the data file, enter the following:
i. Enter the MCD’s county’s name in the County Name field.
ii. Enter the MCD’s name followed by its legal area description (such as town or
township) in the MCD Name and LSAD field.
iii. Enter “active” or “inactive” in the FS Update field.
iv. Enter the effective date when the MCD organized in the Memo field.
b. Enter an ”A” in the Cert. field to inform the Census Bureau that this MCD should be
added to the MAF/TIGER System.
b. If an MCD is no longer organized:
a. Provide the effective date when the MCD ceased to exist in the Memo field.
b. Enter an ”R” in the Cert. field to notify the Census Bureau that the MCD should be
removed from the MAF/TIGER System.
c. If the functional status of an MCD has changed:
a. Enter the correct functional status in the FS Update field.
b. Enter the effective date of the status change in the Memo field.
c. Enter an “E” in the Cert. field to notify the Census Bureau that the functional status
must be edited in the MAF/TIGER System.
d. Upon completion of review of the List 4 data file, the SCO certifies the statement at the bottom
of the file by typing their full name, title, and the date of concurrence below the provided
statement.
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CHAPTER 4

SUBMIT UPDATES TO THE CENSUS BUREAU

All participants must use the Secure Web Incoming Module (SWIM) to submit their changes to
the Census Bureau. Due to security requirements, the Census Bureau cannot accept
submissions through File Transfer Protocol (FTP), email, or any protocol other than the SWIM
site.
To upload and transmit update files to the Census Bureau, first access the SWIM user’s account.
1. Open a web browser window and enter the SWIM URL: .
SWIM runs on the two most recent versions of each of these major browsers:
•
•
•
•

Microsoft Edge®
Google Chrome®
Mozilla Firefox®
Apple Safari®

2. Users who already have a SWIM account should proceed to Step 4 to log in.
3. Users who do not have a SWIM account should select ”Register Account”.
a. Enter the 12-digit token provided by the Census Bureau.
b. Create a password following the five criteria below:
• Username and password are case sensitive.
• It must be at least eight characters in length.
• It must have at least one upper case character.
• It must have at least one lower case character.
• It must have at least one number.
• It must have at least one special character (valid characters are: #, !, $, &, ?, ~).
c. Complete the registration information form.
4. Log in to SWIM using the user’s email address and password.
5. Upload a BAS submission:
a.
b.
c.
d.
e.
f.
g.
h.

Select the “Start New Upload” button.
Select the “BAS” radio button.
Select the “State” radio button for Entity type.
Select the State.
Choose the “+ Add File” button.
Select the .zip file to upload.
Double-click on the .zip file to upload. Add additional .zip files in the same manner.
Add any additional information to the Comments field.

6. Choose “Next”. A “Thank You” screen appears.
7. Logout of SWIM.

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4.1

Troubleshooting SWIM

For those having trouble accessing their SWIM account, here are some tips:
•

SWIM email addresses and passwords are case sensitive.

•

Users who have forgotten their password may reset it by using the “Forgot your password?” link
on the login page. Follow the prompts to enter the case-sensitive email address and provide the
security answer. If the security answer is correct, SWIM sends a password reset link to the email
account to use to reset the password. Once logged into SWIM, users can modify their password
and security answer by selecting the ”Change Security” link at the top, right side of the page.

Figure 5: SWIM Login Screen and Password Reset Link

•

Users that cannot recover their password through the “Forgot your Password?” link should
email with the subject line “SWIM Account Assistance” with a brief
description of the issue.

•

SWIM accounts are specific to the user, not to the government so do not share a SWIM account
between multiple users. Governments may always request another account for a new SCO.

•

If a user has an existing SWIM account through another geographic partnership program such as
the Local Update of Census Addresses (LUCA) operation or the Participant Statistical Areas
Program (PSAP), they may use the same account for BAS. There is no need to create another
account.

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