Block Boundary Suggestion Project Redistricting for Census 2020


In 1975 President Gerald R. Ford signed Public Law 94-171, which stipulates that the U.S. Census Bureau work in a nonpartisan manner with the states to identify and provide the small-area data population counts necessary for legislative redistricting to the governor and the officers or public bodies that have the responsibility for redistricting of each state one year after the Census.

Since the 1980 Census states have used small-area data summarized at the census block and voting district level in redistricting. For the 2020 Census, states can play a more active role by participating in the Block Boundary Suggestion Project (BBSP). States can suggest “hold” and “do not hold” line segments in the prototype 2020 Census blocks using the Census Bureau’s Geographic Update Partnership Software (GUPS) tool.

The Census Bureau works with the State Redistricting Data Program nonpartisan Liaison who is designated by the governor and legislative leadership of the state. The Census & Economic Information Center (CEIC) in the Montana Department of Commerce is the Liaison for Montana and to maintain this nonpartisan relationship, the Census Bureau will only accept completed work from CEIC for BBSP.

BBSP suggestions are performed and submitted to the Census Bureau at a county level. Counties may perform work on the behalf of the State Redistricting Data Program Liaison, CEIC, but all work must be submitted to CEIC for final review and approval. If the State Redistricting Data Program Liaison, CEIC, determines that BBSP work completed by a designee requires changes or additional work, it is the State’s responsibility to decide whether to make the changes at the state level or return the project to the original delineator for further updates.

BBSP files will be submitted to the Census Bureau on a flow basis as each county is completed. This will permit the Census Bureau to review the files early in the process, provide feedback on any errors, omissions, or other concerns.

Note: The number of blocks increased by 35% across the country from Census 2000 to Census 2010. The Census Bureau has acknowledged the need to identify methods for reducing the number of blocks to their Census 2000 tallies. For Montana this will include reducing the number of blocks for Census 2010 to Census 2020 by 36%, 132,228 to 84,307 blocks. Many of the eliminated 2010 blocks were small with no population but many of the prototype block changes may affect redistricting across Montana. Taking an active role in BBSP will assist the Census Bureau in reducing the census block inventory into a more manageable dataset and develop a meaningful inventory of census blocks for Montana.

Five phases of the Redistricting Data Program:
  • Phase 1: Block Boundary Suggestion Project through May 2016
  • Phase 2: Voting District Project Expected December 2017 through May 2019
  • Phase 3: Delivery of the 2020 P.L. 94-171 Redistricting Data Files
  • Phase 4: Collection of Post-2020 Redistricting Plans
  • Phase 5: Review of 2020 Census Redistricting Data Program and Recommendations for Census 2030


Important project links