The Block Boundary Suggestion Project (BBSP) exists so that states can identify non-standard features often used as electoral boundaries (power lines, property lines, or streams) that could serve alongside more traditional features (such as street centerlines) as census tabulation block boundaries. States, through their official liaisons, may also identify features that are not desirable as block boundaries. In addition, legal boundaries reviewed in coordination with the annual Boundary and Annexation Survey also become census tabulation block boundaries.
Where no suggestions are submitted, local precinct boundaries following features the Bureau does not already carry are unlikely to appear as census block edges. The resulting block geography becomes the foundation for the Voting District Project.
The Census Bureau’s deadline to submit BBSP updates was May 29, 2026. Local officials and GIS staff whose jurisdictions did not take part, however, may still have an opportunity to suggest updates to census block geography. State liaisons will continue to make census tabulation block boundary suggestions during the Voting District Project’s initial update cycle in early 2028 and the first verification cycle in early 2029.
A checklist for jurisdictions that did not participate in BBSP
Contact the state’s official liaison. Confirm whether the state participated in the initial BBSP round and what was submitted, and establish how local suggestions will be routed into the VTDP initial update cycle. The Redistricting and Voting Rights Data Office can be reached at rdo@census.gov or 301-763-4039.
Pull the prototype block shapefiles. The Bureau posted the shapefiles and participant guides for BBSP in January 2026 and makes prototype block shapefiles available as a reference for BBSP work. Overlaying them against current precinct boundaries identifies each place a precinct boundary crosses a block boundary rather than following one.
Document every non-standard boundary feature. Compile the precinct boundaries that follow utility easements, drainage corridors, ridgelines, property lines, or unpaved private roads, noting feature type, location, and which precincts each separates. That list is submission-ready material for the next suggestion opportunity.
Review annexations since 2020 and enroll in BAS. Territory annexed since the 2020 Census may not yet be reflected in the Bureau’s geographic data. Legal boundaries reviewed in coordination with the annual Boundary and Annexation Survey also become census tabulation block boundaries.
Begin preparing VTDP submission files. The initial voting district update cycle begins in early 2028, following an announcement the Bureau plans for late 2027. Take time now to compile precinct shapefiles, verify precinct codes and names, and document boundary changes since 2020.
Track the calendar. BBSP verification opens in early 2027, the VTDP initial update cycle begins in early 2028, and block boundary suggestions remain available through the VTDP first verification cycle, planned for early 2029.
In sum, missing the BBSP May 29 deadline does not lock a jurisdiction out of BBSP updates completely. Block boundary suggestions remain available in early 2028 and again in early 2029, and preparing now ensures better redistricting data in 2031. For broader guidance on preparing precinct and district records, including example checklists, see the U.S. Election Assistance Commission’s guide.
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